Image measurement apparatus

ABSTRACT

A first contact target position, a second contact target position, and a characteristic pattern for specifying a position and a posture of the workpiece are set in association with each other. First and second contact target positions for measurement are specified from a workpiece image newly generated during the execution of measurement such that a driving section is controlled to bring the touch probe into contact with the side surface of the workpiece with the specified first contact target position for measurement as a reference, and the driving section is controlled to bring the touch probe into contact with the upper surface of the workpiece with the specified second contact target position for measurement as a reference. Three-dimensional coordinates of a contact point are measured based on a contact signal output when the touch probe comes into contact with the workpiece.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims foreign priority based on Japanese PatentApplication No. 2022-078535, filed May 12, 2022, the contents of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The disclosure relates to an image measurement apparatus that displays aworkpiece image and measures three-dimensional coordinates of theworkpiece using a touch probe.

2. Description of Related Art

Conventionally, there has been known a three-dimensional measurementapparatus in which a workpiece is placed on a stage and a probe isbrought into contact with a desired point on a surface of the workpieceon the stage to measure three-dimensional coordinates of the point withwhich the probe is brought into contact (see, for example, JP2006-234737 A and JP 2004-294311 A).

In JP 2006-234737 A, prior to execution of coordinate measurement, a tipof a probe is brought into contact with three predetermined referencepoints on a surface of a workpiece, and reference coordinates havingthree-dimensional coordinates of the three reference points ascoordinate home positions are set from outputs of a position sensorduring contact. That is, when the tip of the probe is brought intocontact with three points of a first reference point, a second referencepoint, and a third reference point, the first reference point is set asa coordinate home position, an axis passing through coordinates of thefirst reference point and the second reference point is set as an Xaxis, and an axis passing through coordinates of the first referencepoint and the third reference point is set as a Y axis. As a result, adimension and the like can be measured with high accuracy regardless ofa position and a posture of the workpiece.

Further, in JP 2004-294311 A, a camera capable of capturing an image ofa workpiece is mounted separately from a probe.

A measurement site of the probe can be set on a workpiece image acquiredby capturing the image the workpiece by the camera.

Meanwhile, in JP 2006-234737 A, when the reference coordinates are setprior to the execution of the coordinate measurement, an operation ofsequentially bringing the probe into contact with the plurality ofreference points of the workpiece is required, but this operation is atroublesome and requires time and effort for a user.

Further, the measurement point of the probe can be set on the workpieceimage in JP 2004-294311 A, but this is for enabling setting of themeasurement site even for a fine workpiece that is difficult to observewith naked eyes, and it is necessary to set reference coordinates priorto execution of coordinate measurement similarly to JP 2006-234737 A.That is, for example, at the time of continuous measurement in whichthree-dimensional coordinates of a plurality of workpieces of the sametype are sequentially measured, it is necessary to perform an operationof moving the probe to set reference coordinates every time each of theworkpieces is placed on a stage, which is troublesome and requires timeand effort, and hinders easy execution of the measurement.

SUMMARY OF THE INVENTION

The disclosure has been made in view of the above points, and an objectthereof is to enable easy execution of measurement whenthree-dimensional coordinates on a workpiece surface are measured usinga touch probe.

According to one embodiment of the disclosure, an image measurementapparatus includes: a light projecting section which irradiates aworkpiece on a stage with detection light; an imaging section whichreceives the detection light and generates a workpiece image; a touchprobe which outputs a contact signal when coming into contact with theworkpiece on the stage; a driving section which moves at least one ofthe stage and the touch probe with respect to the other to bring thetouch probe into contact with the workpiece placed on the stage; and adisplay section which displays the workpiece image generated by theimaging section at the time of measurement setting. When a direction ofan imaging axis of the imaging section is defined as a Z axis, adirection orthogonal to the Z axis is defined as an X axis, and adirection orthogonal to the Z axis and orthogonal to the X axis isdefined as a Y axis, it is possible to set, on the workpiece imagedisplayed on the display section, a first contact target positionserving as a reference for bringing the touch probe into contact with aside surface of the workpiece in XY directions, a second contact targetposition serving as a reference for bringing the touch probe intocontact with an upper surface of the workpiece in a Z direction, and acharacteristic pattern for specifying a position and a posture of theworkpiece at the time of measurement execution in association with eachother. The set characteristic pattern, a relative positionalrelationship between the first and second contact target positions withrespect to the characteristic pattern, and a fixed positionalrelationship between the imaging section and the touch probe can bestored in a storage section. It is possible to specify a position and aposture of the characteristic pattern stored in the storage section froma workpiece image newly generated for measurement by the imaging sectionat the time of measurement execution and to specify first and secondcontact target positions for measurement based on the specified positionand posture, and the relative positional relationship and the fixedpositional relationship stored in the storage section. It is possible tocontrol the driving section to bring the touch probe into contact withthe side surface of the workpiece with the specified first contacttarget position for measurement as a reference, control the drivingsection to bring the touch probe into contact with the upper surface ofthe workpiece with the specified second contact target position formeasurement as a reference, and to measure three-dimensional coordinatesof a contact point at which the touch probe comes into contact with theworkpiece based on the contact signal output when the touch probe comesinto contact with the workpiece by an operation of the driving section.

That is, at the time of measurement setting, the first contact targetposition serving as the reference for bringing the touch probe intocontact with the side surface of the workpiece and the second contacttarget position serving as the reference for bringing the touch probeinto contact with the upper surface of the workpiece are set on theworkpiece image. Furthermore, the characteristic pattern for specifyingthe position and posture of the workpiece is also set. The relativepositional relationship between the first contact target position andthe second contact target position with respect to the characteristicpattern and the fixed positional relationship between the imagingsection and the touch probe are held in the image measurement apparatus.Thus, when a workpiece image is newly generated at the time ofmeasurement execution, a position and a posture of the workpiece placedon the stage at the time of measurement are specified by applying thecharacteristic pattern to the workpiece image. Further, the first andsecond contact target positions for measurement are specified based onthe relative positional relationship and the fixed positionalrelationship. Then, the touch probe comes into contact with the sidesurface of the workpiece with the specified first contact targetposition for measurement as the reference, and the touch probe comesinto contact with the upper surface of the workpiece with the specifiedsecond contact target position for measurement as the reference. Thethree-dimensional coordinates of the contact point are measured based onthe contact signal output at this time. That is, a user does not need toperform an operation of moving the probe to set a reference coordinateeach time a workpiece is placed on the stage, and thus, the measurementbecomes simple.

According to another embodiment of the disclosure, an edge measurementelement to be used for image measurement is extracted on the workpieceimage at the time of setting the first and second contact targetpositions, and the first and second contact target positions can be setin association with the extracted edge measurement element.

Further, at the time of measurement execution, it is possible to specifyan edge measurement element by executing a pattern search on a workpieceimage newly generated for measurement. In this case, an edge can beextracted from the specified edge measurement element, and the firstcontact target position can be specified based on the extracted edge.

Further, when a setting section sets the first contact target position,it is possible to set a position in the XY directions on the workpieceimage and set a height position in the Z direction.

Further, the setting section can also set path information for causingthe touch probe to approach the workpiece from an operation startposition included in the first contact target position.

Further, the image measurement apparatus may include: a base thatsupports the stage to be movable in a horizontal direction; and asupport section that is connected to the base and supports the imagingsection above the stage. In this case, the first and second contacttarget positions can be set based on absolute coordinates in athree-dimensional space surrounded by the stage, the support section,and the imaging section.

Further, in a case where the workpiece on the stage is located outside avisual field range of the imaging section, it is also possible tocontrol the driving section to move the stage in the XY directions untilthe workpiece enters the visual field range of the imaging section, andcause the imaging section to capture an image of the workpiece enteringthe visual field range when the workpiece enters the visual field range.In a case where a workpiece is larger than the visual field range, it isalso possible to cause the stage to be moved in the XY directions suchthat another part of the workpiece enters the visual field range of theimaging section after imaging is performed for the first time, and then,cause the imaging section to capture an image of the another part of theworkpiece entering the visual field range. A connected image, obtainedby connecting a plurality of the images acquired by performing imaging aplurality of times in this manner, may be used as the workpiece image,and the position and posture of the characteristic pattern can bespecified from the connected image obtained by connecting the pluralityof images.

Further, at the time of measurement execution, a bird's-eye view imageacquired by imaging the entire workpiece using the imaging section oranother imaging section may be displayed on the display section. It isalso possible to receive designation of a search region by the user onthe bird's-eye view image displayed on the display section, and specifythe position and posture of the characteristic pattern by narrowing downto the search region designated by the user.

Further, at the time of measurement execution, it is also possible tocause the display section to display an image, acquired by capturing theworkpiece using the imaging section or another imaging section, andperform ghost display of a preset search region on the display sectionto guide the workpiece to be placed at an appropriate position on thestage. The image to be displayed on the display section at this time canbe a plan-view image of the stage viewed from above, and thus, accuratealignment can be performed.

Since the first and second contact target positions for measurement arespecified based on the position and posture of the characteristicpattern specified from the workpiece image, the relative positionalrelationship between the target position at which the touch probe isbrought into contact with the side surface of the workpiece and thetarget position at which the touch probe is brought into contact withthe upper surface of the workpiece, and the fixed positionalrelationship between the imaging section and the touch probe such thatthe touch probe is brought into contact with the side surface and theupper surface of the workpiece with the specified target positions formeasurement as the references as described above, when three-dimensionalcoordinates on a surface of the workpiece are measured using the touchprobe, the measurement can be easily performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an overall configuration of an imagemeasurement apparatus according to an embodiment of the presentinvention;

FIG. 2 is a perspective view of an apparatus body as viewed from above;

FIG. 3 is a schematic view of the apparatus body as viewed from thefront side;

FIG. 4 is a schematic view of the apparatus body as viewed from thelateral side;

FIG. 5 is a perspective view of a light receiving lens and the vicinitythereof as viewed obliquely from below;

FIG. 6 is a block diagram of the image measurement apparatus;

FIG. 7 is a longitudinal cross-sectional view of a touch probe;

FIG. 8 is a plan view of a fulcrum-forming elastic member;

FIG. 9 is a sectional view taken along line IX-IX in FIG. 7 ;

FIG. 10 is a view corresponding to FIG. 7 and illustrating anotherexample of the touch probe;

FIG. 11 is a perspective view of a changer mechanism of a stylus;

FIG. 12 is a perspective view of a stylus holding section;

FIG. 13 is a flowchart illustrating an example of a stylus mountingprocedure;

FIG. 14A is a perspective view illustrating a state in which a housingis arranged above the stylus holding section at an attachable position;

FIG. 14B is a perspective view illustrating a state in which the housingis lowered and the stylus is mounted;

FIG. 15 is a flowchart illustrating an example of a stylus detachmentprocedure;

FIG. 16 is a flowchart illustrating an example of a procedure at thetime of measurement setting of the image measurement apparatus;

FIG. 17 is a flowchart illustrating an example of an image generationprocedure;

FIG. 18 is a flowchart illustrating an example of a procedure at thetime of measurement setting of image measurement;

FIG. 19 is a flowchart illustrating an example of a procedure at thetime of measurement setting of coordinate measurement;

FIG. 20 is a perspective view of a workpiece on a stage;

FIG. 21 is a planar image of the stage on which the workpiece is placed;

FIG. 22 is a longitudinal cross-sectional view of the workpiece on thestage along a Y direction;

FIG. 23 is a view illustrating an example of a user interface screen forsetting a contact target position;

FIG. 24 is a view illustrating an example of the user interface screenfor setting the contact target position with respect to an inclinedsurface;

FIG. 25 is a flowchart illustrating an example of a procedure ofmeasurement using a non-contact displacement meter;

FIG. 26 is a view illustrating an example of a user interface screen fordisplaying a geometric element;

FIG. 27 is a view illustrating an example of a user interface screen forsuperimposing and displaying the geometric element on athree-dimensional image;

FIG. 28 is a flowchart illustrating an example of a detailed procedureof a measurement operation of the touch probe;

FIG. 29A is a flowchart illustrating an example of a procedure of thefirst half during the measurement execution of the image measurementapparatus;

FIG. 29B is a flowchart illustrating an example of a procedure of thesecond half during the measurement execution of the image measurementapparatus;

FIG. 30 is a flowchart illustrating an example of a procedure ofnon-contact measurement at the time of measurement execution;

FIG. 31 is a diagram corresponding to FIG. 6 according to a firstmodified example including a three-channel imaging element; and

FIG. 32 is a diagram corresponding to FIG. 6 according to a secondmodified example including a single-channel imaging element and athree-channel imaging element.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings. Note that the following preferredembodiments are described merely as examples in essence, and there is nointention to limit the present invention, its application, or its use.

FIG. 1 is a diagram illustrating an overall configuration of an imagemeasurement apparatus 1 according to an embodiment of the presentinvention. The image measurement apparatus 1 includes an apparatus body2, a control unit 3 configured using a personal computer or the like,and a display section 4, and is configured to be capable of performingarithmetic processing on data, acquired by the apparatus body 2, in thecontrol unit 3 to measure a dimension of each portion of a workpiece W,and also executing quality determination or the like of a measurementresult as necessary. The control unit 3 may be incorporated in andintegrated with the apparatus body 2. Although details will be describedlater, the data acquired by the apparatus body 2 includes data on acontact point when a touch probe 80, which will be described later,comes into contact with the workpiece W, data measured by a non-contactdisplacement meter 70 (illustrated in FIG. 3 ), and the like in additionto image data of the workpiece W.

The display section 4 displays, for example, various setting screens,image data, a measurement result, and the like. The display section 4includes, for example, a liquid crystal display, an organic EL display,or the like. The display section 4 is illustrated as a separate memberfrom the apparatus body 2 and the control unit 3 in the present example,but may be incorporated in the apparatus body 2 or the control unit 3without being limited thereto.

The image measurement apparatus 1 further includes a keyboard 5, a mouse6, and the like as operation devices for a user. The operation device isnot limited to the keyboard 5 and the mouse 6, and may be a touch paneloperation device or the like. For example, the control unit 3 can alsobe configured using a laptop personal computer, and in this case, thekeyboard 5 and the mouse 6 are provided in a form of being integratedwith the control unit 3 together with the display section 4.

The image measurement apparatus 1 further includes a storage section 7.The storage section 7 can be configured using, for example, a hard diskdrive, a solid-state drive, or the like, and is a part that storesvarious types of data acquired by the apparatus body 2, information setby the user, an image, a measurement result, a quality determinationresult, and the like. The storage section 7 may be built in the controlunit 3 or may be provided outside the control unit 3. In a case wherethe storage section 7 is provided outside the control unit 3, thestorage section 7 may be, for example, a cloud storage or the likeconnected via a communication line such as the Internet.

(Configuration of Apparatus Body 2) As illustrated in FIG. 2 , theapparatus body 2 includes a base 20 and a stage 21 that is horizontallymovable with respect to the base 20. Note that the stage 21 is movableup and down. In the vicinity of the central portion of the stage 21, aplacement table 21 a made of a member that transmits light, such asglass, is provided, and the workpiece W can be placed on the placementtable 21 a. The stage 21 is supported by the base 20 so as to be movablein the horizontal direction (an X direction which is a width directionof the apparatus body 2 and a Y direction which is a depth direction ofthe apparatus body 2). That is, the apparatus body 2 includes anXY-direction driving section 23 (schematically illustrated in FIGS. 3and 4 ) that drives the stage 21, and the XY-direction driving section23 can move the stage 21 within a predetermined range in the X directionand within a predetermined range in the Y direction. Not only the stage21 is linearly moved in the X direction and linearly moved in the Ydirection but also the stage 21 can be moved such that a movementtrajectory is inclined with respect to an X axis and a Y axis in planview, or the stage 21 can be moved so as to draw an arbitrary curve.

The XY-direction driving section 23 includes an X-direction linear scale23 a configured to detect a movement distance in the X direction and aY-direction linear scale 23 b configured to detect a movement distancein the Y direction. The X-direction linear scale 23 a enables detectionof a position and the movement distance of the stage 21 in a left-rightdirection. The Y-direction linear scale 23 b enables detection of aposition and the movement distance of the stage 21 in the depthdirection.

The XY-direction driving section 23 is controlled by the control unit 3.The XY-direction driving section 23 is controlled based on a controlsignal output from the control unit 3, a current position of the stage21 is determined based on detection signals of the X-direction linearscale 23 a and the Y-direction linear scale 23 b, the stage 21 is movedto a desired position, and the stage 21 is moved so as to draw a desiredmovement trajectory.

Although a Z direction is referred to as an up-down direction or aheight direction, the X direction is referred to as the left-rightdirection, and the Y direction is referred to as a front-rear directionin the description of the present embodiment, this is for convenience ofthe description and does not limit a posture of the apparatus body 2during use. Further, the user is usually on the front side of theapparatus body 2 in many cases, a side of the apparatus body 2 closer tothe user is simply referred to as the front, a side opposite to the useris simply referred to as the rear, a right side as viewed from the useris simply referred to as the right side, and a left side as viewed fromthe user is simply referred to as the left side.

As illustrated in FIGS. 3 and 4 , a transmission illumination 30 as alight projecting section is provided in a lower part of the base 20below the stage 21. As illustrated in FIG. 4 , the transmissionillumination 30 includes: a transmission illumination light emitter 31having, for example, a light emitting diode or the like; a slit 32through which light emitted from the transmission illumination lightemitter 31 is transmitted; a mirror 33 configured to direct the lighttransmitted through the slit 32 upward; and a lens 34 on which the lightdirected upward by the mirror 33 is incident. The lens 34 is a lenscapable of emitting the incident light as parallel light. The lightemitted from the lens 34 is directed to the placement table 21 a of thestage 21, is transmitted through the placement table 21 a, and isemitted to the workpiece W placed on the placement table 21 a frombelow.

As illustrated in FIG. 2 , a measurement start button 2 a is provided onthe front side of the base 20 of the apparatus body 2. The measurementstart button 2 a is a button configured to be operated by the user atthe time of starting the measurement of the workpiece W. A measurementoperation is executed only by pressing the measurement start button 2 aonce at the time of executing the measurement.

The apparatus body 2 includes a support section 22 and a measurementexecution section 24. As illustrated in FIGS. 3 and 4 , the supportsection 22 is connected to a rear part of the base 20 and extends upwardfrom the rear part of the base 20. The measurement execution section 24is supported by an upper part of the support section 22. The measurementexecution section 24 is provided with a coaxial epi-illumination 40, aring illumination 45, an imaging section 50, a non-contact displacementmeter 70, a housing 81 of the touch probe 80, and the like.

The measurement execution section 24 is configured separately from thesupport section 22, and is movable in the Z direction with respect tothe support section 22. That is, the apparatus body 2 includes aZ-direction driving section 25 that drives the measurement executionsection 24, and the measurement execution section 24 is linearly movablefrom an ascending end position to a descending end position by theZ-direction driving section 25. An imaging axis of the imaging section50 coincides with the Z axis, and thus, the imaging axis extends in theZ direction. The measurement execution section 24 is an example of amovable unit that moves along an imaging axis of the imaging section 50.

The Z-direction driving section 25 includes a Z-direction linear scale25 a configured to detect a movement distance in the Z direction, andthe Z-direction linear scale 25 a can detect a height of the measurementexecution section 24, the movement distance in the height direction, andthe like. The Z-direction driving section 25 is controlled by a controlsection 3 d included in the control unit 3. The control section 3 dcontrols the Z-direction driving section 25 by a control signal,determines a current position of the measurement execution section 24based on a detection signal of the Z-direction linear scale 25 a, andmoves the measurement execution section 24 to a desired position. Amoving speed of the measurement execution section 24 can be changed in aplurality of stages or continuously.

The coaxial epi-illumination 40 is a light projecting section, andincludes a coaxial epi-illumination light emitter 41 having, forexample, a light emitting diode or the like, a lens 42 on which lightemitted from the coaxial epi-illumination light emitter 41 is incident,and a direction conversion member 43 that directs the light emitted fromthe lens 42 downward as illustrated in FIG. 4 . The direction conversionmember 43 is configured using a light transmitting member capable oftransmitting light in the up-down direction. The light emitted from thedirection conversion member 43 is detection light. The detection lightemitted from the direction conversion member 43 is directed to theplacement table 21 a of the stage 21, and is emitted from above to theworkpiece W placed on the placement table 21 a, that is, the workpiece Won the stage 21.

The imaging section 50 includes a light receiving lens 51, a beamsplitter 52, a high-magnification-side image forming lens 53, alow-magnification-side image forming lens 54, a high-magnification-sideimaging element 55, and a low-magnification-side imaging element 56, andthese constitute a first imaging section. The imaging section 50 issupported by the support section 22 in a posture with an imagingdirection being a normal direction of the stage 21 (the Z direction)above the stage 21.

Specifically, as also illustrated in FIG. 5 , the light receiving lens51 of the imaging section 50 is disposed on a lower surface of themeasurement execution section 24, and is positioned such that a lightreceiving surface faces an upper surface of the placement table 21 a ofthe stage 21. Therefore, detection light emitted from the coaxialepi-illumination 40 and reflected by the surface of the workpiece W canbe received by the light receiving lens 51, and light emitted from thetransmission illumination 30 can also be received by the light receivinglens 51.

An optical axis of the light receiving lens 51 coincides with the Zdirection. In the present example, the direction conversion member 43 ofthe coaxial epi-illumination 40 is located directly above the lightreceiving lens 51, and thus, detection light emitted from the coaxialepi-illumination 40 is transmitted through the light receiving lens 51and emitted to the workpiece W on the stage 21.

The beam splitter 52 is disposed above the direction conversion member43, and is configured using a prism that causes light emitted upwardfrom the light receiving lens 51 to branch in two directions. As thebeam splitter 52, for example, a cube beam splitter or a plate beamsplitter can be used. The cube beam splitter is preferable since lightpassing through the beam splitter is not refracted as compared with theplate beam splitter so that an optical axis does not deviate, andalignment adjustment of a branch angle is easy. In the present example,light incident on the beam splitter 52 via the light receiving lens 51branches into the upper side and the rear side. Thus, thehigh-magnification-side image forming lens 53 is disposed on the upperside of the beam splitter 52, and the low-magnification-side imageforming lens 54 is disposed on the rear side of the beam splitter 52.Further, the high-magnification-side imaging element 55 is disposed onthe upper side of the high-magnification-side image forming lens 53, andlight incident on the high-magnification-side image forming lens 53forms an image on a light receiving surface of thehigh-magnification-side imaging element 55. Further, thelow-magnification-side imaging element 56 is disposed on the rear sideof the low-magnification-side image forming lens 54, and light incidenton the low-magnification-side image forming lens 54 forms an image on alight receiving surface of the low-magnification-side imaging element56.

The high-magnification-side imaging element 55 and thelow-magnification-side imaging element 56 are configured using acharge-coupled device (CCD) image sensor, a complementary MOS (CMOS)image sensor, and the like. A workpiece image acquired by thelow-magnification-side imaging element 56 is a low-magnification image,and a workpiece image acquired by the high-magnification-side imagingelement 55 is a high-magnification image having a higher magnificationthan the low-magnification image. In the present example, each of thehigh-magnification-side imaging element 55 and thelow-magnification-side imaging element 56 is configured using asingle-channel imaging element to acquire a high-resolution workpieceimage in order to enhance measurement accuracy. Accordingly, theworkpiece images output from the high-magnification-side imaging element55 and the low-magnification-side imaging element 56 become monochromeimages (grayscale images).

A focal position of the imaging section 50 is adjusted by theZ-direction driving section 25. That is, the control section 3 d canmove the measurement execution section 24 in the Z direction bycontrolling the Z-direction driving section 25, but the imaging section50 can be moved along an imaging axis since the Z direction coincideswith a direction of the imaging axis of the imaging section 50. That is,the Z-direction driving section 25 is a focus adjustment mechanism thatadjusts the focal position of the imaging section 50, and the focus ofthe imaging section 50 can be adjusted by the movement of themeasurement execution section 24 in the direction along the imagingaxis. In the focus adjustment, not only autofocus using an algorithmsuch as a conventionally known contrast scheme or phase differencescheme but also manual focus in which the user performs a predeterminedoperation for adjustment is also possible.

The above-described configuration of a bifurcated optical systemincluding the light receiving lens 51 and the beam splitter 52 enablessimultaneous acquisition of the high-magnification image and thelow-magnification image without mechanically switching the opticalsystem. Note that the configuration of the bifurcated optical systemusing the beam splitter 52 may be omitted, and a high-magnification lensand a low-magnification lens may be mechanically switched to acquire thehigh-magnification image and the low-magnification image.

The ring illumination 45 is a light projecting section that irradiatesthe workpiece W on the stage 21 with monochromatic light (white light)or detection light having a plurality of different wavelengths. Examplesof the detection light having the plurality of different wavelengthsinclude red light, green light, and blue light. The ring illumination 45has a circular shape surrounding the outer periphery of the lightreceiving lens 51, and is arranged coaxially with the light receivinglens 51 below the light receiving lens 51.

As illustrated in FIG. 6 , the ring illumination 45 includes a red lightsource 45 a that emits red light, a green light source 45 b that emitsgreen light, and a blue light source 45 c that emits blue light. Each ofthe red light source 45 a, the green light source 45 b, and the bluelight source 45 c is configured using a light emitting diode or thelike, and can be individually turned on and off. That is, the workpieceW is illuminated with red light by turning on only the red light source45 a, the workpiece W is illuminated with green light by turning on onlythe green light source 45 b, the workpiece W is illuminated with bluelight by turning on only the blue light source 45 c, and the workpiece Wis illuminated with white light by turning on all of the red lightsource 45 a, the green light source 45 b, and the blue light source 45c.

The ring illumination 45 includes an illumination Z-direction drivingsection 45 d, and the ring illumination 45 is linearly movable from anascending end position to a descending end position by the illuminationZ-direction driving section 45 d. As the ring illumination 45 is movedaccording to a height of the workpiece W, detection light can be emittedfrom a place close to the workpiece W. The illumination Z-directiondriving section 45 d includes a Z-direction linear scale 45 e configuredto detect a movement distance in the Z direction, and the Z-directionlinear scale 45 e can detection a height of the ring illumination 45,the movement distance in the height direction, and the like. Note thatthe ring illumination 45 is arranged outside a casing of the measurementexecution section 24 in the present embodiment, but the presentinvention is not limited thereto, and the ring illumination 45 may bearranged inside the housing of the measurement execution section 24.

As illustrated in FIG. 3 , the mirror 33 that guides the transmissionillumination 30 to the stage 21, the ring illumination 45, the directionconversion member 43 that guides the coaxial epi-illumination 40 to thestage 21, and the imaging section 50 (for example, thehigh-magnification-side imaging element 55) are arranged substantiallylinearly in the vertical direction. Then, the ring illumination 45, thedirection conversion member 43, and the imaging section 50 are fixed tothe casing of the measurement execution section 24 movable up and downto be integrally movable in the Z direction. In addition, in the presentembodiment, a housing 81 of the touch probe 80, which will be describedlater, is also fixed to the casing of the measurement execution section24 such that the housing 81 is also integrally movable in the Zdirection.

The measurement execution section 24 includes a first stage camera 46, asecond stage camera 47, and a front camera 48. Since the measurementexecution section 24 is provided in the upper part of the supportsection 22, the first stage camera 46, the second stage camera 47, andthe front camera 48 are also provided in the upper part of the supportsection 22. Each of the first stage camera 46, the second stage camera47, and the front camera 48 includes an imaging element capable ofacquiring a color image. Further, the first stage camera 46, the secondstage camera 47, and the front camera 48 have fewer pixels than thehigh-magnification-side imaging element 55 and thelow-magnification-side imaging element 56, but may have substantiallythe same number of pixels without being limited thereto.

As illustrated in FIG. 4 , the first stage camera 46 and the secondstage camera 47 are disposed on the front side of the light receivinglens 51, and are provided to be spaced apart from each other in theleft-right direction. Imaging directions (optical-axis directions) ofthe first stage camera 46 and the second stage camera 47 are the same asthe imaging direction of the imaging section 50. Imaging visual fieldsof the first stage camera 46 and the second stage camera 47 are locatedon the front side of an imaging visual field of the imaging section 50,and can capture an image of a front part of the stage 21. Note that thefirst stage camera 46 or the second stage camera 47 captures an image ofthe entire stage 21 in a bird's-eye view manner from directly above togenerate a bird's-eye view image (planar image), and may be referred toas a bird's-eye view image generating section.

The front camera 48 is a second imaging section that captures an imageof the workpiece W in a posture with an imaging direction beingdifferent from the normal direction of the stage 21 above the stage 21to generate a bird's-eye view image, and can also be referred to as thebird's-eye view image generating section. The front camera 48 isdisposed on the front side of the light receiving lens 51, and ispositioned on the front side of the first stage camera 46 and the secondstage camera 47 in a positional relationship in the front-reardirection. Therefore, it can be said that the front camera 48 is acamera disposed closest to the user. An imaging visual field of thefront camera 48 is set to be wider than imaging visual fields of thehigh-magnification-side imaging element 55 and thelow-magnification-side imaging element 56, includes the imaging visualfields of the high-magnification-side imaging element 55 and thelow-magnification-side imaging element 56, and can also capture an imageof the outside of the imaging visual fields of thehigh-magnification-side imaging element 55 and thelow-magnification-side imaging element 56. In the present example, thefront camera 48 can capture an image of the entire upper surface of thestage 21. Further, the front camera 48 is a camera that is configured tobe capable of capturing an image in real time and can acquire alive-view image.

The imaging direction (optical-axis direction) of the front camera 48 isdirected from obliquely above on the front side of the stage 21 to theupper surface of the stage 21, that is, from the front to the back whenviewed from the user. This is to make a line-of-sight direction when thestage 21 is viewed from the user at the time of measurement executionsubstantially coincide with the imaging direction of the front camera48. As a result, the bird's-eye view image generated by the front camera48 corresponds to what the user can see when viewing the workpiece W ina bird's-eye view manner with a natural measurement posture.

(Configuration of Non-Contact Displacement Meter 70)

The non-contact displacement meter 70 is a non-contact measuring sectionthat emits measurement light along the normal direction of the stage 21and receives reflected light from the workpiece W on the stage 21 tomeasure a height of the workpiece W on the stage 21 in a non-contactmanner. The non-contact displacement meter 70 is a laser coaxialdisplacement meter, more specifically, a white confocal displacementmeter, and includes a lens unit 71, a light projecting and receivingunit 72, and an optical fiber section 73 connecting both the units 71and 72 as illustrated in FIG. 3 . The light projecting and receivingunit 72 is built in the base 20, and includes a laser light source 72 a,a light source optical member 72 b, a phosphor 72 c, and a lightreceiving element 72 d.

The laser light source 72 a is configured to emit light having a singlewavelength, and preferably emit blue or ultraviolet light having awavelength of 450 nm or less. In particular, when blue light is emitted,it is possible to project, onto the workpiece W, light in which lightthat has been used to excite the phosphor 72 c and has undergonewavelength conversion and light that has not been used to excite thephosphor 72 c but remains blue are mixed.

The phosphor 72 c is excited by the light from the laser light source 72a and emits light converted to have a different wavelength. The phosphor72 c includes one or a plurality of kinds of phosphors 72 c, and may be,for example, excited by blue light and emit light converted into yellowlight, or two kinds of phosphors 72 c may be used to excited by bluelight and emit light converted into green and to be excited by bluelight and emit light converted into red.

The optical fiber section 73 includes one or a plurality of opticalfibers. A ferrule 73 a may be used at an end of the optical fiber inorder to facilitate handling. A core diameter of an emission end, whichis an end of the optical fiber section 73 on the lens unit 71 side, canbe set to 200 μm or less in diameter and may be set to 50 μm or less indiameter because of the influence on a diameter of a spot formed on theworkpiece W.

The phosphor 72 c is fixed to an incident end side of the optical fibersection 73. The phosphor 72 c may be fixed in a light-transmissivemedium such as resin or glass that transmits light from the laser lightsource 72 a and light emitted by the phosphor 72 c, and thelight-transmissive medium may be fixed to the incident end of theoptical fiber section 73. At this time, a refractive index of thelight-transmissive medium is set to be equal to or lower than arefractive index of a core on the incident end side of the optical fibersection 73 in order to cause the light from the laser light source 72 aand the light from the phosphor 72 c to be efficiently incident on theoptical fiber section 73.

The light receiving element 72 d is configured using an imaging elementsuch as a multi-division photodiode (PD), a CCD, or a CMOS, andselectively receives light from the workpiece W according to awavelength via a spectroscope 72 e configured using a diffractiongrating, a prism, or the like, a color selection optical filter, or thelike. The light receiving element 72 d may receive light from theworkpiece W via the optical fiber section 73 or may receive light viaanother optical path.

The lens unit 71 is attached to the measurement execution section 24,and thus, is movable in the Z direction together with the imagingsection 50. The lens unit 71 is a member configured to collect lightemitted from the emission end of the optical fiber section 73 toward theworkpiece W, and includes an upper lens 71 a and a lower lens 71 b. Thelens unit 71 is arranged at the right of the imaging section 50 and hasan optical axis extending in the Z direction.

When the lens unit 71 is configured to have a confocal position with theemission end of the optical fiber section 73, the light from theworkpiece W is separated according to a wavelength by the spectroscope72 e configured using a diffraction grating, a prism, or the like, and awavelength-luminance distribution of the light from the workpiece W isdetected based on a light receiving position in the light receivingelement 72 d. A signal related to the light receiving position and alight receiving amount of the light receiving element 72 d istransmitted to a displacement measuring section 3 c provided in thecontrol unit 3.

For example, in a case where a chromatic aberration lens is used as thelens unit 71, the displacement measuring section 3 c illustrated in FIG.6 evaluates that the workpiece W exists at a closer distance when lighthaving a shorter wavelength is detected, and that the workpiece W existsat a farther distance when light having a longer wavelength is detected.Further, in a case where a diffractive lens is used as the lens unit 71,the displacement measuring section 3 c measures the displacement of theworkpiece W by evaluating that the workpiece W exists at a fartherdistance when light having a shorter wavelength is detected and that theworkpiece W exists at a closer distance when light having a longerwavelength is detected.

As illustrated in FIG. 3 , a focal length of the non-contactdisplacement meter 70 is set to be longer than a focal length of theimaging section 50. Further, a focal height of the non-contactdisplacement meter 70 is set to be substantially the same as a focalheight of the imaging section 50. That is, an attachment height of thelens unit 71 of the non-contact displacement meter 70 with respect tothe measurement execution section 24 and an attachment height of theimaging section 50 with respect to the measurement execution section 24can be arbitrarily set, but in the present example, a height of the lensunit 71 and a height of the imaging section 50 are set such that thefocal height of the non-contact displacement meter 70 and the focalheight of the imaging section 50 are substantially the same. Forexample, the lower lens 71 b of the lens unit 71 is disposed above thelight receiving lens 51 of the imaging section 50.

Since the non-contact displacement meter 70 can be moved by theZ-direction driving section 25 in the present example, for example, whenthe focal length of the imaging section 50 and the focal length of thenon-contact displacement meter 70 are matched, the height measurement bythe non-contact displacement meter 70 can be executed only by moving thestage 21 in the horizontal direction such that the non-contactdisplacement meter 70 is focused on a measurement target position at thefocal length of the imaging section 50.

(Configuration of Touch Probe) The touch probe 80 illustrated in FIG. 3is a member that outputs a contact signal when coming into contact withthe workpiece W on the stage 21. In the present example, the touch probe80 is provided in the measurement execution section 24, and thus, theZ-direction driving section 25 can relatively move the touch probe 80with respect to the stage 21 in the Z direction. Further, the stage 21can be relatively moved in the XY directions with respect to the touchprobe 80 by the XY-direction driving section 23. In this manner, theZ-direction driving section 25 and the XY-direction driving section 23move at least one of the stage 21 and the touch probe 80 with respect tothe other such that the touch probe 80 can be brought into contact withthe workpiece W placed on the stage 21. Note that the stage 21 may bemoved in the Z direction, or the touch probe 80 may be moved in the XYdirections. An axis orthogonal to the Z axis and coinciding with theleft-right direction of the apparatus body 2 is defined as the X axis.An axis orthogonal to the Z axis and coinciding with a direction(front-rear direction of the apparatus body 2) orthogonal to the X axisis defined as the Y axis.

The contact signal output from the touch probe 80 is transmitted to acoordinate measuring section 3 b of the control unit 3 illustrated inFIG. 6 . When receiving the contact signal output when the touch probe80 is brought into contact with the workpiece W by the Z-directiondriving section 25 and the XY-direction driving section 23, thecoordinate measuring section 3 b measures three-dimensional coordinatesof the contact point at which the touch probe 80 comes into contact withthe workpiece W based on the contact signal.

For example, a position in the X direction and a position in the Ydirection of the stage 21 when the contact signal of the touch probe 80is output can be acquired by the X-direction linear scale 23 a and theY-direction linear scale 23 b, respectively. Further, a position of thetouch probe 80 in the Z direction when the contact signal of the touchprobe 80 is output can be acquired by the Z-direction linear scale 25 a.Further, when a relative positional relationship between the touch probe80 and the workpiece W is set in advance and calibration of the imagingsection 50 or the like is executed, the three-dimensional coordinates ofthe contact point can be measured based on detection results of thelinear scales 23 a, 23 b, and 25 a.

As illustrated in FIG. 7 , the touch probe 80 includes the housing 81, aprobe shaft 82, a stylus 83, a fulcrum-forming elastic member (firstelastic member) 84, a home-position-returning elastic member (secondelastic member) 85, and a displacement detection mechanism 86. Thehousing 81 has a tubular shape extending in the Z direction, is fixed tothe measurement execution section 24, and is disposed at the left of theimaging section 50 as illustrated in FIG. 5 . Therefore, the imagingsection 50 is interposed between the touch probe 80 and the lens unit 71of the non-contact displacement meter 70.

As illustrated in FIG. 7 , the probe shaft 82 is a rod-like memberprovided inside the housing 81 and extends in the Z direction. An uppercylindrical member 82 a having a diameter larger than an outer diameterof the probe shaft 82 is fixed to a lower end of the probe shaft 82. Thestylus 83 is also configured using a rod-like member extending in the Zdirection similarly to the probe shaft 82, but is thinner than the probeshaft 82. A contact portion 83 b that has a spherical shape and comesinto contact with the workpiece W is provided at a lower end portion ofthe stylus 83.

An upper end portion of the stylus 83 is detachably attached to a lowersurface of the cylindrical member 82 a of the probe shaft 82 That is,the lower cylindrical member 83 a having a larger diameter than theouter diameter of the stylus 83 is fixed to the upper end portion of thestylus 83. The upper cylindrical member 82 a and the lower cylindricalmember 83 a have substantially the same diameter, but a dimension in theup-down direction is set to be longer in the lower cylindrical member 83a. Note that the probe shaft 82 is integrated with the housing 81, andthus, it can be said that the stylus 83 is detachably attached to thehousing 81.

Although an attachment and detachment structure of the stylus 83 withrespect to the probe shaft 82 is not particularly limited, for example,a kinematic mount or the like can be used. That is, permanent magnets(not illustrated) having polarities to be attracted to each other arefixed to the lower surface of the upper cylindrical member 82 a and anupper surface of the lower cylindrical member 83 a. For example, threesteel balls 83 c are fixed at equal intervals in the circumferentialdirection around the magnet on one of the lower surface of the uppercylindrical member 82 a and the upper surface of the lower cylindricalmember 83 a, and fitting grooves (not illustrated) in which the steelballs 83 c are fitted are formed around the magnet on the other surfaceso as to correspond to positions of the steel ball 83 c. As a result,when the stylus 83 is brought closer to the probe shaft 82 from belowthe probe shaft 82, the stylus 83 is held in a state of being attractedto the probe shaft 82 by an attraction force of the magnets fixed to theupper cylindrical member 82 a and the lower cylindrical member 83 a.Alternatively, when the probe shaft 82 is brought closer to the stylus83 from above the stylus 83, the stylus 83 is held in a state of beingattracted to the probe shaft 82 by the attraction force of the magnetsfixed to the upper cylindrical member 82 a and the lower cylindricalmember 83 a. At this time, the stylus 83 is arranged coaxially with theprobe shaft 82 as the steel balls 83 c are fitted in the fittinggrooves.

When the stylus 83 is removed from the probe shaft 82, the stylus 83 ismoved downward against a magnetic force with the probe shaft 82 beingfixed thereto, or the probe shaft 82 is moved upward against themagnetic force with the stylus 83 being fixed thereto. As a result, thelower cylindrical member 83 a is separated from the upper cylindricalmember 82 a, and the stylus 83 is removed.

The fulcrum-forming elastic member 84 is a member connected to thehousing 81 and the probe shaft 82 to form a deflection fulcrum of theprobe shaft 82, and is configured using, for example, a flat spring orthe like. Specifically, the fulcrum-forming elastic member 84 isconfigured using a leaf spring extending along an extension line in theradial direction of the probe shaft 82 and having a radially outer endportion connected to an inner surface of the housing 81. An example of ashape of the fulcrum-forming elastic member 84 is illustrated in FIG. 8, and an outer shape of the fulcrum-forming elastic member 84 is acircle formed along the inner surface of the housing 81. An insertionhole 84 a through which the probe shaft 82 can be inserted is formed ina central portion of the fulcrum-forming elastic member 84, and theprobe shaft 82 is fixed in a state of being inserted into the insertionhole 84 a. In the fulcrum-forming elastic member 84, an outer portion 84b, an inner portion 84 c in which the insertion hole 84 a is formed, andthree connecting portions 84 d connecting the outer portion 84 b and theinner portion 84 c are integrally molded.

The fulcrum-forming elastic member 84 can be made of an elastic materialhaving an axial shape restoring property. Further, the material and theshape of the fulcrum-forming elastic member 84 are set such that a statein which the inner portion 84 c is located at the axial center ismaintained and a radial deviation is suppressed. As a result, thedeflection fulcrum of the probe shaft 82 can be kept by thefulcrum-forming elastic member 84. Further, when the stylus 83 comesinto contact with the workpiece W, the fulcrum-forming elastic member 84is deformed with a small force that does not affect contact resistance.Further, since the probe shaft 82 can be displaced in the Z directionwith a small force, the fulcrum-forming elastic member 84 is configuredsuch that the inner portion 84 c can be displaced in the Z directionwith a small force relative to the outer portion 84 b.

As illustrated in FIG. 7 , a support section 81 a configured to supportthe outer portion 84 b (illustrated in FIG. 8 ) of the fulcrum-formingelastic member 84 from below is provided inside the housing 81. Sincethe outer portion 84 b is supported by the support section 81 a, theprobe shaft 82 is held at a predetermined height set in advance andstabilized, and is less likely to vibrate, so that the measurementaccuracy is improved.

The home-position-returning elastic member 85 is a member that isconnected to the housing 81 and the probe shaft 82 at a part away fromthe fulcrum-forming elastic member 84 in the axial direction of theprobe shaft 82 to return the probe shaft 82 to a home position. In thismanner, the fulcrum-forming elastic member 84 configured to form thedeflection fulcrum and the home-position-returning elastic member 85configured for returning to the home position are separately provided,and the respective elastic members 84 and 85 are designed to satisfymutually different functions. That is, a displacement suppressing forcein the radial direction of the probe shaft 82 is set to be stronger inthe fulcrum-forming elastic member 84 than in thehome-position-returning elastic member 85, and a biasing force forbiasing the probe shaft 82 toward the home position is set to bestronger in the home-position-returning elastic member 85 than in thefulcrum-forming elastic member 84.

The home-position-returning elastic member 85 is provided closer to adistal end side (lower side) of the probe shaft 82 than thefulcrum-forming elastic member 84, includes three or more tensionsprings 85 a, 85 b, and 85 c that extend radially from the probe shaft82 along the extension line in the radial direction of the probe shaft82 and have outer end portions connected to the housing 81 asillustrated in FIG. 9 , and is set such that spring forces of the threeor more tension springs 85 a, 85 b, and 85 c are balanced. Although thethree tension springs 85 a, 85 b, and 85 c constitute thehome-position-returning elastic member 85 in the present example, thenumber of the tension springs 85 a, 85 b, and 85 c is not limitedthereto.

Inner end portions of the tension springs 85 a, 85 b, and 85 c are fixedto an outer surface of the probe shaft 82, and such three fixingportions are arranged at equal intervals (120° intervals) in thecircumferential direction. Axes of the tension springs 85 a, 85 b, and85 c are orthogonal to an axis of the probe shaft 82, and extensionlines of the axes of the tension springs 85 a, 85 b, and 85 c intersecton the axis of the probe shaft 82. The tension springs 85 a, 85 b, and85 c have the same spring constant.

Here, it is assumed that the probe shaft 82 is displaced in anydirection of the three tension springs 85 a, 85 b, and 85 c. In a casewhere a balance is made at a position where the tension spring 85 a iscontracted by ΔA, the remaining tension spring 85 b and tension spring85 c are in a relationship of A/2 displacement based on vector division.A strength of each of the remaining tension spring 85 b and tensionspring 85 c acts in half in a direction of the tension spring 85 a toeventually having a relationship of adding half of a spring strength ofthe tension spring 85 a, and a balance is made while applying strengthof 1.5×ΔA in total. Since the three tension springs 85 a, 85 b, and 85 chave the same spring constant, only the spring constant×ΔA×1.5 and thespring constant are design parameters. That is, when the same springconstant is set for the tension springs 85 a, 85 b, and 85 c, the touchprobe 80 that makes low-pressure contact can be obtained even if alength for maintaining the balance varies.

Further, there is a possibility that an elastic limit may be exceeded orthe probe shaft 82 may be deformed if an excessive stroke is applied tothe probe shaft 82 since the touch probe 80 that makes low-pressurecontact is used. For this reason, it is sometimes desirable to provide alimiting mechanism for protection and adopt a configuration that isacceptable when a stronger external force is received. For example, in acase where it is assumed that the contact portion 83 b is stronglypushed in the X direction, if the limiting mechanism for such a case islocated above the probe shaft 82 receives a bending force, which mayinduce deformation of the probe shaft 82. That is, if thehome-position-returning elastic member 85 is located above thefulcrum-forming elastic member 84, the probe shaft 82 having receivedthe large external force in the X direction as described above mayreceive the bending force. In the present example, thehome-position-returning elastic member 85 is provided below thefulcrum-forming elastic member 84 to make the probe shaft 82 less likelyreceive the bending force. Note that the above-described problem is notapplied to all cases, and thus, the home-position-returning elasticmember 85 can also be provided above the fulcrum-forming elastic member84.

Further, for example, the probe shaft 82 is radially pulled by the threetension springs 85 a, 85 b, and 85 c having the same spring constant,and thus, displacement of an amount reduced by the principle of leverageat a ratio of H1/H2 (illustrated in FIG. 7 ) relative to an amount ofmovement of the contact portion 83 b is applied to the tension springs85 a, 85 b, and 85 c with respect to the home position where a balanceis made with predetermined elongation, and a difference from the balancecan be calculated only by the displacement and the spring constant. Forexample, when it is assumed that the contact with the workpiece W isdetected at an extremely low contact pressure of about 2 g, the springconstant is derived backward, so that an extremely simple relationshipcan be established. Due to this relationship, even if the tensionsprings 85 a, 85 b, and 85 c are configured using springs havingrelatively firm strengths, a resistance force at the contact portion 83b does not excessively increase, and the touch probe 80 that makeslow-pressure contact can be obtained.

As illustrated in FIG. 7 , displacement detection mechanisms 86A, 86B,and 86C are magnetic sensors that detect displacement of the probe shaft82 in three-dimensional directions in a non-contact manner, and areprovided closer to a proximal end side (upper side) of the probe shaft82 than the fulcrum-forming elastic member 84. Specifically, thedisplacement detection mechanisms 86A, 86B, and 86C include: theZ-direction displacement detection mechanism 86A (first displacementdetection mechanism) that detects displacement in the Z direction (firstdirection) along the axial direction of the probe shaft 82; theX-direction displacement detection mechanism 86B (second displacementdetection mechanism) that detects displacement in the X direction(second direction) along the radial direction of the probe shaft 82; andthe Y-direction displacement detection mechanism 86C (third displacementdetection mechanism) that detects displacement in the Y direction (thirddirection) extending along the radial direction of the probe shaft 82and orthogonal to the Z direction.

The Z-direction displacement detection mechanism 86A includes aZ-direction detection magnet 86 a in which an N pole and an S pole arearranged side by side in the Z direction, and a Z-direction magneticsensor 86 b. The Z-direction detection magnet 86 a is fixed to the probeshaft 82, and the Z-direction magnetic sensor 86 b is fixed to thehousing 81. The Z-direction magnetic sensor 86 b is arranged so as toface a boundary part between the N-pole and the S-pole of theZ-direction detection magnet 86 a. Therefore, when the probe shaft 82 isdisplaced even slightly in the Z direction, a magnetic field detected bythe Z-direction magnetic sensor 86 b changes, whereby the displacementof the probe shaft 82 in the Z direction can be detected in anon-contact manner.

A magnet fixing member 82 b is provided at an upper end portion of theprobe shaft 82. The X-direction displacement detection mechanism 86Bincludes an X-direction detection magnet 86 c in which an N pole and anS pole are arranged side by side in the X direction, and an X-directionmagnetic sensor 86 d. The X-direction detection magnet 86 c is fixed toan upper surface of the magnet fixing member 82 b, and the X-directionmagnetic sensor 86 d is fixed to the housing 81. The X-directionmagnetic sensor 86 d is arranged so as to face a boundary part betweenthe N-pole and the S-pole of the X-direction detection magnet 86 c.Therefore, when the probe shaft 82 slightly swings in the X directionabout the deflection fulcrum and is displaced, a magnetic field detectedby the X-direction magnetic sensor 86 d changes, whereby thedisplacement of the probe shaft 82 in the X direction can be detected ina non-contact manner.

The Y-direction displacement detection mechanism 86C includes aY-direction detection magnet 86 e in which an N pole and an S pole arearranged side by side in the Y direction, and a Y-direction magneticsensor 86 f. The Y-direction detection magnet 86 e is fixed to a siteaway from the X-direction detection magnet 86 c on the upper surface ofthe magnet fixing member 82 b, and the Y-direction magnetic sensor 86 fis fixed to the housing 81. The Y-direction magnetic sensor 86 f isarranged so as to face a boundary part between the N-pole and the S-poleof the Y-direction detection magnet 86 e. Therefore, when the probeshaft 82 slightly swings in the Y direction about the deflection fulcrumand is displaced, a magnetic field detected by the Y-direction magneticsensor 86 f changes, whereby the displacement of the probe shaft 82 inthe Y direction can be detected in a non-contact manner.

The displacement detection mechanism 86 may be a sensor other than themagnetic sensor, and may be, for example, an optical or capacitivedetection sensor.

Damping grease for generating a damping force is applied to the tensionsprings 85 a, 85 b, and 85 c. The damping grease has a high viscosityand a nonvolatile paste shape, and is applied to the tension springs 85a, 85 b, and 85 c so as to fill gaps among lines of the tension springs85 a, 85 b, and 85 c. As a result, it is possible to apply the dampingforce many times in a short time when the tension springs 85 a, 85 b,and 85 c elongate and contract, desired damping is easily obtained, andfurther, it is unnecessary to apply excessive damping which is likely tocause noise.

Note that the damping grease or the like can be made effective in adistant place where a damping effect is easily enhanced based on theprinciple of leverage when the tension springs 85 a, 85 b, and 85 c aredamped. For example, a gap between the Z-direction detection magnet 86 aand the Z-direction magnetic sensor 86 b, a gap between the X-directiondetection magnet 86 c and the X-direction magnetic sensor 86 d, and agap between the Y-direction detection magnet 86 e and the Y-directionmagnetic sensor 86 f may be filled with the damping grease. Further, thetension springs 85 a, 85 b, and 85 c may be damped using other dampingmembers.

FIG. 10 is a view illustrating another example of the touch probe 80. Inthe present example, an orientation of the X-direction magnetic sensor86 d of the X-direction displacement detection mechanism 86B and anorientation of the Y-direction magnetic sensor 86 f of the Y-directiondisplacement detection mechanism 86C are different from those in theabove-described example. Specifically, the X-direction magnetic sensor86 d and the X-direction detection magnet 86 c are arranged so as toface each other in the horizontal direction, and the Y-directionmagnetic sensor 86 f and the Y-direction detection magnet 86 e arearranged so as to face each other in the horizontal direction.

(Changer Mechanism of Stylus) Examples of the stylus 83 include across-shaped stylus, an L-shaped stylus, a T-shaped stylus, and the likehaving different overall shapes, styluses having different diameters,styluses whose contact portions 83 b at tips have different sizes, andthe like, and are selectively used according to the workpiece W,measurement applications, and the like. As illustrated in FIGS. 1 and 2, the support section 22 of the apparatus body 2 is provided with achanger mechanism (exchanger) 100 that holds different styluses 83A,83B, and 83C and automatically exchange desired styluses at apredetermined timing. In the present example, the touch probe 80 isprovided on the left side of the measurement execution section 24, andthus, the changer mechanism 100 is provided on the left side of thesupport section 22 so as to correspond thereto. Note that the changermechanism 100 may be provided on the right side of the support section22 in a case where the touch probe 80 is provided on the right side ofthe measurement execution section 24.

FIG. 11 is a perspective view of the changer mechanism 100 of thestylus. The changer mechanism 100 includes a stylus holding section 101that holds one or a plurality of styluses, an arm section 102 thatsupports the stylus holding section 101, a changer rotation drivingsection (rotating section) 103 that rotates the arm section 102, and achanger feed driving section (slider section) 104 that moves the stylusholding section 101 along the arm section 102.

As illustrated in FIG. 12 , the stylus holding section 101 includesfirst to third cutout portions 101 a, 101 b, and 101 c that hold thestyluses 83A, 83B, and 83C of different types, respectively. Each of thecutout portions 101 a, 101 b, and 101 c is opened in the up-downdirection and also opened to one side in the horizontal directions, andopening directions are the same in all the cutout portions 101 a, 101 b,and 101 c. Note that FIG. 12 illustrates the third cutout portion 101 cfrom which a member forming an upper part has been removed for thepurpose of describing an internal structure, but the third cutoutportion 101 c also has the same shape as the first cutout portion 101 aand the second cutout portion 101 b. Note that the number of the cutoutportions is not limited to three, and may be set to any number.

Holding claws 101 d configured to hold the stylus are provided,respectively, at intermediate portions of the cutout portions 101 a, 101b, and 101 c in the up-down direction. The holding claw 101 d is made ofa member having elasticity such as resin, and has a shape that is openedin the same direction as the opening part in the horizontal direction ofeach of the cutout portions 101 a, 101 b, and 101 c. Both end portionsof the holding claw 101 d protrude from an inner surface of each of thecutout portions 101 a, 101 b, and 101 c, and both the end portions ofthe holding claw 101 d are engaged with a groove 83 d formed in an outerperipheral surface of the lower cylindrical member 83 a of the stylus83. A dimension of the groove 83 d in the up-down direction is set to belonger than a dimension of the holding claw 101 d in the up-downdirection, and a difference between the dimensions allows the stylusheld by the holding claw 101 d to relatively move up and down withrespect to the holding claw 101 d.

An interval between both the end portions of the holding claw 101 d isnarrower than an outer diameter of a part of the lower cylindricalmember 83 a where the groove 83 d is formed. When the lower cylindricalmember 83 a is held, the part of the lower cylindrical member 83 a wherethe groove 83 d is formed is pressed against both the end portions ofthe holding claw 101 d from the opening side of the holding claw 101 d,so that the holding claw 101 d is elastically deformed to widen theinterval between both the end portions. As a result, the part of thelower cylindrical member 83 a where the groove 83 d is formed can beinserted into the inner side of the holding claw 101 d from a gapbetween both the end portions of the holding claw 101 d and engaged withthe holding claw 101 d. When the lower cylindrical member 83 a held bythe holding claw 101 d is to be removed, the lower cylindrical member 83a is relatively moved in the opening direction of the holding claw 101d, so that the holding claw 101 d is elastically deformed to widen theinterval between both the end portions, and the lower cylindrical member83 a is withdrawn from the opening side of the holding claw 101 d.

The arm section 102 illustrated in FIG. 11 is a member configured tomove between an attachable position where the styluses 83A, 83B, and 83C(reference signs 83B and 83C are illustrated in FIG. 2 ) held by thestylus holding section 101 can be attached to the housing 81 and aretracted position retracted from the attachable position. Theattachable position may also be referred to as a stylus attachmentpreparation position, and the retracted position may also be referred toas a stylus storage position. Specifically, the arm section 102 isconfigured using a member extending in the horizontal direction, and hasa proximal end portion being attached to the support section 22 via thechanger rotation driving section 103. The changer rotation drivingsection 103 is configured using an electric motor having a rotary shaft103 a extending in the Z direction. The rotary shaft 103 a is parallelto the imaging axis of the imaging section 50, and a proximal end sideof the arm section 102 is connected to a lower end portion of the rotaryshaft 103 a.

As indicated by a broken line in FIG. 2 , the changer rotation drivingsection 103 is disposed above the stage 21. FIG. 2 illustrates a statein which the styluses 83A, 83B, and 83C held by the stylus holdingsection 101 are moved to the retracted position. The stylus holdingsection 101 and the styluses 83A, 83B, and 83C at the retracted positionare arranged so as not to interfere during measurement setting andduring measurement execution, specifically, such that the stylus holdingsection 101 and the styluses 83A, 83B, and 83C do not enter a movablerange of the measurement execution section 24 or the imaging visualfield of the imaging section 50.

The support section 22 includes an eave portion 22A that covers at leasta portion of an upper portion of the stylus holding section 101 at theretracted position. The eave portion 22A is formed to project leftwardfrom a left wall of the support section 22, and the stylus holdingsection 101 can be arranged immediately below the eave portion 22A. As aresult, it is possible to prevent surrounding articles and the like fromcoming into contact with the stylus holding section 101 and the styluses83A, 83B, and 83C held by the stylus holding section 101. The eaveportion 22A may be formed to cover the entire upper portion of thestylus holding section 101.

As illustrated in FIG. 11 , the arm section 102 is provided with thechanger feed driving section 104. The changer feed driving section 104includes a feeding electric motor 104 a, a screw rod 104 b rotationallydriven by the feeding electric motor 104 a, and a threaded member 104 cthreaded to the screw rod 104 b. The feeding electric motor 104 a isfixed to the proximal end portion of the arm section 102, and a rotationcenter line thereof is oriented in the longitudinal direction of the armsection 102. The screw rod 104 b is arranged in parallel with the armsection 102 and is supported to be rotatable with respect to the armsection 102. The stylus holding section 101 is fixed to the threadedmember 104 c.

The arm section 102 is provided with a guide rail 102 a that guides thestylus holding section 101 in the longitudinal direction of the armsection 102. The stylus holding section 101 is movable only in thelongitudinal direction of the arm section 102 in a state of beingengaged with the guide rail 102 a not to be rotatable. That is, thestyluses 83A, 83B, and 83C held by the stylus holding section 101 can bemoved in a direction orthogonal to the imaging axis.

When the screw rod 104 b is rotated by the feeding electric motor 104 a,the stylus holding section 101 can be moved to a distal end side of thearm section 102 as illustrated in FIG. 11 , and the stylus holdingsection 101 can be moved to the proximal end side of the arm section 102or the vicinity thereof although not illustrated. The stylus holdingsection 101 can be stopped at any position relative to the arm section102. The position of the stylus holding section 101 is detected by aposition detector such as a rotary encoder and output to the controlsection 3 d.

FIG. 11 illustrates a state in which the styluses 83A, 83B, and 83C heldby the stylus holding section 101 are moved to the attachable positionwhere attachment to the housing 81 is possible. A position of thechanger rotation driving section 103 is set such that the rotary shaft103 a of the changer rotation driving section 103 is positioned betweenthe styluses 83A, 83B, and 83C at the attachable position and thestyluses 83A, 83B, and 83C at the retracted position, and the changerrotation driving section 103 at such a position is attached to thesupport section 22.

The changer rotation driving section 103 rotates the arm section 102 by180° when moving the stylus holding section 101 from the retractedposition to the attachable position and from the attachable position tothe retracted position That is, the position of the stylus holdingsection 101 can be greatly switched from the front side to the rear sideand from the rear side to the front side of the changer rotation drivingsection 103.

Next, an outline of stylus exchange will be described. FIG. 13 is aflowchart illustrating an example of a stylus mounting procedure. Instep SA1 after the start, the control section 3 d of the control unit 3controls the Z-direction driving section 25 to move the measurementexecution section 24 to an upper standby position. In step SA2, thecontrol section 3 d controls the changer feed driving section 104 tomove the stylus holding section 101 in the longitudinal direction of thearm section 102 such that a desired cutout portion (set to be the firstcutout portion 101 a) among the first to third cutout portions 101 a,101 b, and 101 c is arranged at a predetermined position. As a result,the stylus holding section 101 moves outward from a space immediatelybelow the eave portion 22A (for example, the stylus holding section 101moves to the vicinity of the center of the arm section 102 and exits tothe outer side of the eave portion 22A). In step SA3, the controlsection 3 d controls the changer rotation driving section 103 to rotatethe arm section 102 such that the stylus holding section 101 is arrangedat the attachable position. This state is illustrated in FIG. 14A ofFIG. 14 . Since the measurement execution section 24 is at the upperstandby position, the stylus 83A is not yet mounted to the housing 81.Note that the position of the stylus holding section 101 may be finelyadjusted along the longitudinal direction of the arm section 102 afterstep SA3.

Thereafter, the flow proceeds to step SA4, and the control section 3 dcontrols the Z-direction driving section 25 to lower the measurementexecution section 24 to be moved to a mounting height. Then, the lowercylindrical member 83 a of the stylus 83A is attracted to the uppercylindrical member 82 a of the probe shaft 82 by a magnetic force. Astate after the attraction is illustrated in FIG. 14B of FIG. 14 . Next,the flow proceeds to step SA5, where the control section 3 d controlsthe changer rotation driving section 103 to rotate the arm section 102such that the stylus holding section 101 is arranged at the retractedposition. At this time, the holding claw 101 d is elastically deformedso that the lower cylindrical member 83 a comes out of the holding claw101 d.

Next, a procedure for detaching the stylus attached to the housing 81 isillustrated in FIG. 15 . In step SB1 after the start, the controlsection 3 d of the control unit 3 controls the Z-direction drivingsection 25 to move the measurement execution section 24 to the mountingheight similarly to step SA4. In step SB2, the control section 3 dcontrols the changer feed driving section 104 to move the stylus holdingsection 101 in the longitudinal direction of the arm section 102 suchthat a desired cutout portion (set to be the first cutout portion 101 a)among the first to third cutout portions 101 a, 101 b, and 101 c isarranged at a predetermined position. At this time, the cutout portionwhere no stylus is held is arranged at the predetermined position.Further, the stylus holding section 101 moves outward from a spaceimmediately below the eave portion 22A (for example, the stylus holdingsection 101 moves to the vicinity of the center of the arm section 102and exits to the outer side of the eave portion 22A).

In step SB3, the control section 3 d controls the changer rotationdriving section 103 to rotate the arm section 102 such that the stylusholding section 101 is arranged at the attachable position. This flow isa flow during the detachment, and thus, does not correspond to an“attachable” state, but the stylus holding section 101 is at the sameposition as the “attachable position” in the flow illustrated in FIG. 13, and thus, the “attachable position” is also used in this flow. The“attachable position” may be replaced with a “detachable position”. Thisstate is the same as that illustrated in FIG. 14B of FIG. 14 , and theholding claw 101 d is engaged with the part of the lower cylindricalmember 83 a of the stylus 83A where the groove 83 d is formed.

Thereafter, the flow proceeds to step SB4, and the control section 3 dcontrols the Z-direction driving section 25 to raise the measurementexecution section 24 to be moved to the upper standby position. Then,the upper cylindrical member 82 a of the probe shaft 82 relatively movesupward with respect to the lower cylindrical member 83 a of the stylus83A, and the lower cylindrical member 83 a of the stylus 83A iswithdrawn from the upper cylindrical member 82 a of the probe shaft 82against a magnetic force. A state after the withdrawal is the same asthat illustrated in FIG. 14A of FIG. 14 . Next, the flow proceeds tostep SB5, where the control section 3 d controls the changer rotationdriving section 103 to rotate the arm section 102 such that the stylusholding section 101 is arranged at the retracted position.

As described above, the control section 3 d controls the changerrotation driving section 103 and the changer feed driving section 104such that the stylus held by the stylus holding section 101 is arrangedto the attachable position from the retracted position, and controls thechanger rotation driving section 103 and the changer feed drivingsection 104 such that the stylus held by the stylus holding section 101is arranged to the retracted position from the attachable position.Further, the control section 3 d controls the changer feed drivingsection 104 such that the stylus holding section 101 at the retractedposition is positioned closer to the proximal end side of the armsection 102 than the stylus holding section 101 at the attachableposition.

Note that the holding claw 101 d is configured to be engaged with thegroove 83 d formed on the outer peripheral surface of the lowercylindrical member 83 a in the present embodiment, but a modifiedexample in which the groove 83 d is not formed is also conceivable. Forexample, a movable member (preferably an elastic member) that isrelatively movable (abuts or separates) in the radial direction withrespect to the outer peripheral surface of the lower cylindrical member83 a may be provided on the inner side of each of the cutout portions101 a to 101 c. The movable member may be moved by the control section 3d. In this case, in step SA4 described above, the control section 3 dcontrols the movable member to separate from the outer peripheralsurface of the lower cylindrical member 83 a after the lower cylindricalmember 83 a of the stylus 83A is attracted to the upper cylindricalmember 82 a of the probe shaft 82. Further, in step SB4 described above,the control section 3 d controls the movable member to abut on the outerperipheral surface of the lower cylindrical member 83 a before themeasurement execution section 24 is raised and moved to the upperstandby position. In this manner, attachment and detachment operationsof the stylus 83A may be realized without forming the groove 83 d on theouter peripheral surface of the lower cylindrical member 83 a.

(Configuration of Control Unit)

The control unit 3 illustrated in FIG. 6 includes, for example, acentral processing unit (CPU), a RAM, a ROM, an internal bus, and thelike (not illustrated). The CPU is connected to the display section 4,the keyboard 5, the mouse 6, the storage section 7, and the apparatusbody 2 via the internal bus. The control unit 3 acquires operationstates of the keyboard 5, the mouse 6, the measurement start button 2 aof the apparatus body 2, and the like. Further, the control unit 3 canacquire image data acquired by the imaging section 50, the first stagecamera 46, the second stage camera 47, and the front camera 48 of theapparatus body 2. Further, a result of the calculation in the controlunit 3, the image data acquired by the imaging section 50, the firststage camera 46, the second stage camera 47, and the front camera 48,and the like can be displayed on the display section 4.

Further, the control unit 3 controls the Z-direction driving section 25,the XY-direction driving section 23, the coaxial epi-illumination 40,the ring illumination 45, the illumination Z-direction driving section45 d, the imaging section 50, the non-contact displacement meter 70, thetouch probe 80, the changer rotation driving section 103, the changerfeed driving section 104, and the like of the apparatus body 2.Specifically, the control unit 3 is connected to each hardware via theinternal bus, and thus, controls the operation of the above-describedhardware and executes various software functions according to a computerprogram stored in the storage section 7. For example, the control unit 3is provided with an image measuring section 3 a that measures adimension of the workpiece W based on a workpiece image generated by theimaging section 50, the coordinate measuring section 3 b that measuresthree-dimensional coordinates of a contact point at which the touchprobe 80 comes into contact with the workpiece W, the displacementmeasuring section 3 c that measures displacement of the workpiece W onthe stage 21 based on an output signal from the non-contact displacementmeter 70, and the like. The displacement measurement is also referred toas height measurement.

Hereinafter, details of functions that can be executed by the controlunit 3 will be described separately for the time of measurement settingbefore measurement of the workpiece W and the time of measurementexecution in which the measurement of the workpiece W is executed.

(At Time of Measurement Setting)

FIG. 16 is a flowchart illustrating an example of a procedure at thetime of measurement setting of the image measurement apparatus 1. Instep SC1 after the start, a plan-view image is generated. That is, animage of the stage 21 is captured by the imaging section 50. At thistime, a workpiece image is acquired in a case where the user places theworkpiece W on the placement table 21 a of the stage 21. For example,the imaging section 50 can be used to capture the image of the workpieceW on the stage 21 after the measurement execution section 24 is moved bythe Z-direction driving section 25 to move the imaging section 50 to ameasurement position, and can also be used for illumination asnecessary.

In step SC2, a bird's-eye view image is generated. An image of theworkpiece W on the stage 21 is captured by the front camera 48 after themeasurement execution section 24 is moved by the Z-direction drivingsection 25 to move the front camera 48 to the measurement position.

When the front camera 48 is used to capture the image of the workpieceW, the following control can be performed. That is, first, the controlsection 3 d detects a position of the workpiece W on the stage 21 basedon the workpiece image generated by the imaging section 50. Thereafter,the control section 3 d determines whether or not the workpiece W on thestage 21 is located within a visual field range of the front camera 48based on the detected position of the workpiece W on the stage 21 andthe known visual field range of the front camera 48. Next, when theworkpiece W on the stage 21 is located outside the visual field range ofthe front camera 48, the control section 3 d controls the XY-directiondriving section 23 to move the stage 21 such that the workpiece W on thestage 21 is located within the visual field range of the front camera48. As a result, the front camera 48 can reliably capture the image ofthe workpiece W on the stage 21.

Further, after the image of the workpiece W on the stage 21 is capturedby the front camera 48, the control section 3 d can also control theXY-direction driving section 23 to move the stage 21 such that the frontcamera 48 can capture an image of another region on the stage 21.

Position information of the stage 21 when a bird's-eye view image iscaptured by the front camera 48 can be acquired by the X-directionlinear scale 23 a or the Y-direction linear scale 23 b. The acquiredposition information of the stage 21 and the bird's-eye view image canbe stored in the storage section 7 in association with each other. As aresult, the position of the stage 21 when the bird's-eye view image iscaptured can be grasped.

In step SC3, it is determined whether or not to generate a colorworkpiece image (color image) based on a result selected by the user.Color image generation is selected on a user interface screen displayedon the display section 4 if the user desires to generate a color image,and the color image generation is not selected if not. The user'sselection operation is performed by the keyboard 5, the mouse 6, or thelike, and is received by a receiving section 3 e of the control unit 3.

If the user does not desire to generate a color image, that is, if it isdetermined not to generate a color image in step SC3, the flow proceedsto step SC4, and a grayscale workpiece image (grayscale image) isgenerated based on data acquired by the imaging section 50 withillumination of monochromatic light. On the other hand, if the userdesires to generate a color image, that is, if it is determined togenerate a color image in step SC3, the flow proceeds to step SC5, andthe color image is generated.

The image generation in each of steps SC4 and SC5 will be described indetail based on a flowchart illustrated in FIG. 17 . In step SD1 afterthe start of FIG. 17 , the workpiece W is illuminated by thetransmission illumination 30. In step SD2, the XY-direction drivingsection 23 is controlled to move the stage 21 in the X direction or theY direction, and the workpiece W is searched for while causing theimaging section 50 to capture an image thereof. The stage 21 is moved ina spiral shape from the center in the X direction and the center in theY direction, for example. Then, when a proportion of black pixels(pixels having luminance values equal to or less than a predeterminedvalue) in the image captured by the imaging section 50 becomes equal toor more than a certain value, it is determined that the workpiece W ispresent in this region. In this manner, the workpiece W can be searchedfor, a position of the workpiece W on the stage 21 can be specified, anda size of the workpiece W, a part occupied by the workpiece W on thestage 21, and the like can be specified.

In step SD3, the imaging section 50 captures an image of the workpiece Wsearched for in step SD2. At this time, when a grayscale image is to begenerated, the imaging section 50 captures the image in a state in whichthe red light source 45 a, the green light source 45 b, and the bluelight source 45 c of the ring illumination 45 are all turned on toilluminate the workpiece W with white light.

On the other hand, when a color image is to be generated, theabove-described grayscale workpiece image is acquired, and further, acolor information generating section 3 f of the control unit 3 generatescolor information of the workpiece W based on a plurality of workpieceimages generated by the imaging section 50 each time each beam offdetection light having a plurality of different wavelengths is emittedfrom the ring illumination 45. Specifically, a workpiece image duringred illumination captured by the imaging section 50 with only the redlight source 45 a turned on, a workpiece image during green illuminationcaptured by the imaging section 50 with only the green light source 45 bturned on, and a workpiece image during blue illumination captured bythe imaging section 50 with only the blue light source 45 c turned onare generated. The color information generating section 3 f acquires hueand saturation as the color information from these three workpieceimages.

The control section 3 d generates a color image obtained by adding thecolor information of the workpiece generated by the color informationgenerating section 3 f to the grayscale workpiece image. Here, an RGBimage including three channels of red, green, and blue can be convertedinto an HSV image including hue (H), saturation (S), and a value ofbrightness (V). The color information corresponds to the hue (H) and thesaturation (S). It is possible to generate a new color image byassigning desired color information to the hue (H) and the saturation(H) with a single-channel image as the value of brightness (V) in orderto add the color information to the single-channel image. In the presentexample, the color image is generated by combining the hue andsaturation acquired by the color information generating section 3 f witha value of brightness of the grayscale workpiece image. Note that acolor space is not limited to HSV, and handling using another colorspace such as HLS is also possible.

When a color image is to be generated, the grayscale workpiece image isan image directly used for measurement, and thus, is obtained using ahigh-magnification image captured by the high-magnification-side imagingelement 55, and the workpiece images for generating the colorinformation, that is, the workpiece image during red illumination, theworkpiece image during green illumination, and the workpiece imageduring blue illumination are obtained using low-magnification imagescaptured by the low-magnification-side imaging element 56. Therefore,the color image is acquired by adding the color information generatedbased on the low-magnification images to the grayscale workpiece imagewhich is the high-magnification image. Since a depth becomes deeper inimaging by the low-magnification-side imaging element 56, it is possibleto acquire the color information of a wide range and a deep depth in ashort time by acquiring the workpiece images for generating the colorinformation by the low-magnification-side imaging element 56. Theacquired color information can be added to the workpiece image capturedby the high-magnification-side imaging element 55 with a shallow depth.

As the grayscale workpiece image, an image captured under differentcapturing conditions (exposure, illumination intensity, illuminationtype, lens magnification, and the like) from the workpiece images forgenerating the color information can be used. In addition, the colorinformation may be added to workpiece images obtained under differentillumination conditions, focus conditions, and the like. Further, evenif an image captured in real time by the imaging section 50 has a singlechannel, the color information acquired by the color informationgenerating section 3 f can be added.

Next, the flow proceeds to step SD4. In step SD4, it is determinedwhether or not it is necessary to capture an image of a part adjacent toa range whose image is captured in step SD3. The search result in stepSD2 is used in this determination. When the workpiece W is also presentoutside the range whose image is captured in step SD3 and it isnecessary to capture the image of the part, it is determined as YES instep SD4, and the flow proceeds to step SD5. In step SD5, theXY-direction driving section 23 is controlled to move the stage 21 suchthat another part of the workpiece W enters the imaging visual field ofthe imaging section 50. Thereafter, the flow proceeds to step SD3, andan image of a part different from a part captured for the first time iscaptured by the imaging section 50. Steps SD5 and SD3 are repeated asmany times as necessary, and a connection process of connecting aplurality of workpiece images thus acquired is executed. That is, thecontrol section 3 d controls the XY-direction driving section 23 and theimaging section 50, generates the plurality of workpiece images fordifferent sites of the workpiece, and generates a connected image, whichis an image of a region wider than the imaging visual field of theimaging section 50, by connecting the plurality of generated workpieceimages. The color information of the workpiece generated by the colorinformation generating section 3 f is added to the connected image aswell. As a result, the color connected image can be acquired. Note thatadditional imaging is unnecessary if it is determined as NO in step SD4,and thus, this flow is ended.

Thereafter, the flow proceeds to step SC6 of the flowchart illustratedin FIG. 16 . In step SC6, the control section 3 d causes the displaysection 4 to display the color image when the color image is generatedin step SC5, and causes the display section 4 to display the grayscaleimage when the grayscale image is generated in step SC4. Further, whenthe connected image is generated, the control section 3 d causes thedisplay section 4 to display the color connected image or the grayscaleconnected image. Further, when a live-view image is generated, thecontrol section 3 d causes the display section 4 to display a colorlive-view image or a grayscale live-view image.

In step SC6, a bird's-eye view image captured by the front camera 48 canalso be displayed on the display section 4. When the front camera 48captures a plurality of bird's-eye view images, the plurality ofbird's-eye view images can be displayed as thumbnails on the displaysection 4. That is, the respective bird's-eye view images are reduced insize and displayed side by side in a predetermined direction. When theuser selects any one reduced image, the control section 3 d causes thedisplay section 4 to display the bird's-eye view image corresponding tothe selected reduced image.

In step SC7, a measurement instrument is determined. The measurementinstruments include the image measuring section 3 a that measures adimension of the workpiece W based on the workpiece image, thecoordinate measuring section 3 b that measures three-dimensionalcoordinates using the touch probe 80, and the displacement measuringsection 3 c that measures displacement using the non-contactdisplacement meter 70. The user can select any measurement instrumentamong the image measuring section 3 a, the coordinate measuring section3 b, and the displacement measuring section 3 c. For example, when anoperation of selecting the measurement instrument is performed on a userinterface screen displayed on the display section 4, such a selectionoperation is received by the receiving section 3 e.

The flow proceeds to step SC8 if it is determined in step SC7 that theimage measuring section 3 a is selected, proceeds to step SC9 if it isdetermined that the coordinate measuring section 3 b is selected, andproceeds to step SC10 if it is determined that the displacementmeasuring section 3 c is selected.

Details of a case where image measurement is selected (step SC8) areillustrated in a flowchart illustrated in FIG. 18 . In step SE1 afterthe start, the control section 3 d changes an imaging condition to animaging condition corresponding to the image measurement of theworkpiece W. The imaging condition includes illumination, exposure time,and the like.

In step SE2, the receiving section 3 e receives a shape type designatedby the user. In step SE3, the receiving section 3 e receives designationof an edge extraction region performed by the user. The edge extractionregion can be set to be a region extracted as an edge on a workpieceimage and used for measurement. In step SE4, the imaging section 50captures an image of the workpiece W on the stage 21. In step SE5, aplurality of edge points are detected on the workpiece image acquired instep SE4. The edge point can be detected based on a change in aluminance value on the workpiece image. In step SE6, a fitting linepassing through the plurality of edge points is calculated. Thereafter,in step SE7, the image measuring section 3 a calculates the dimensionusing the fitting line. The image measuring section 3 a measures thedimension of the workpiece W based on a high-magnification imagegenerated by the high-magnification-side imaging element 55.

Details of a case where coordinate measurement is selected (step SC9)are illustrated in a flowchart illustrated in FIG. 19 . Steps SF1 to SF6after the start are the same as SE1 to SE6 in the flowchart illustratedin FIG. 18 . Thereafter, in step SF7, a scan line for the coordinatemeasurement, that is, a scan line of the touch probe 80 is calculated.In step SF8, a measurement operation using the touch probe 80 isperformed. Thereafter, a fitting line is calculated again in step SF9,and then, the coordinate measuring section 3 b calculates the dimensionin step SF10.

Here, details of the coordinate measurement will be described with aspecific example. FIG. 20 is a perspective view illustrating a state inwhich the workpiece W is placed on the stage 21, and FIG. 21 is a planarimage obtained by capturing an image of the state in which the workpieceW is placed on the stage 21 from above. In FIGS. 20 and 21 , absolutecoordinates in a three-dimensional space surrounded by the stage 21, thesupport section 22 (illustrated in FIG. 2 and the like), and the imagingsection 50 are indicated by X, Y, and Z.

The workpiece W includes a side surface S1 extending along the Zdirection, an upper surface S2 extending along the XY directions, aninclined surface S3 inclined at a predetermined tilt angle with respectto the Z direction, and a hole H1 that is open on the upper surface S2and extends along the Z direction. Further, an alignment mark M forpositioning is provided on the upper surface S2.

At the time of measurement setting, a plan-view image of the workpieceas illustrated in FIG. 21 is displayed on the display section 4. On theworkpiece image displayed on the display section 4, the user sets afirst contact target position P1 serving as a reference for bringing thetouch probe 80 into contact with the side surface S1 of the workpiece Win the XY directions, a second contact target position P2 serving as areference for bringing the touch probe 80 into contact with the uppersurface S2 of the workpiece W in the Z direction, and a characteristicpattern for specifying a position and a posture of the workpiece W atthe time of measurement execution in association with each other. Theabove-described setting can be performed by a setting section 3 g of thecontrol unit 3. Note that the “first contact target position P1” and the“second contact target position P2” referred to here are conceptsincluding not only a contact point at which the touch probe 80 isbrought into contact with the workpiece W, but also operation startposition and end position and the like to be described later.

In the present example, the characteristic pattern is the alignment markM. When the characteristic pattern is to be set, the user operates themouse 6 or the like to designate a region such that the characteristicpattern is included on the workpiece image as indicated by a rectangularframe line 200 in FIG. 21 . A method of setting the characteristicpattern is not limited to the illustrated example, and a region may bedesignated using a free curve, and a method of designating only thecharacteristic pattern may be used. Further, the characteristic patternmay be set by a method in which the setting section 3 g performsautomatically extraction.

The characteristic pattern may be a shape, a pattern, a color, a symbol,a character, or the like of a portion of the workpiece W, and can alsobe referred to as characteristic amount information. Further, thecharacteristic pattern only needs to be information for specifying theposition and posture of the workpiece W at the time of measurementexecution on the workpiece image displayed on the display section 4, andmay be any type of information. The characteristic amount informationmay include a plurality of the characteristic patterns.

In FIG. 21 , a third contact target position P3 and a fourth contacttarget position P4 are also set. The third contact target position P3 isa position serving as a reference for bringing the touch probe 80 intocontact with an inner surface of the hole H1 of the workpiece W in theXY directions, and the fourth contact target position P4 is a positionserving as a reference for bringing the touch probe 80 into contact withthe inclined surface S3 of the workpiece W in a normal direction of theinclined surface S3. The setting section 3 g can set the third contacttarget position P3, the fourth contact target position P4, and thecharacteristic pattern in association with each other.

A plurality of the first contact target positions P1 can be set based onthe absolute coordinates, can be set to be spaced apart from each otherin the Y direction as illustrated in FIG. 21 , and can be set to bespaced apart from each other in the Z direction as illustrated in FIG.22 . As illustrated in FIGS. 22 and 23 , the display section 4 candisplay a longitudinal cross section of the workpiece W. Each settingcan also be performed on the longitudinal cross section of the workpieceW.

As surrounded by a frame line 201 in FIG. 21 , the setting section 3 gextracts and sets the side surface S1 of the workpiece W as a first edgemeasurement element (straight edge element) on the workpiece image. Thefirst edge measurement element corresponds to an outer surface of theworkpiece W, and thus, can be accurately and clearly extracted byillumination using the transmission illumination 30. The setting section3 g sets the first edge measurement element in association with theextracted first contact target position P1. In addition to the automaticsetting described above, the user can manually set the edge by operatingthe mouse 6 or the like.

For example, a user interface screen 210 for setting a contact targetposition as illustrated in FIG. 23 can generated by the control section3 d and displayed on the display section 4. The user interface screen210 for setting is provided with a cross section display region 211 inwhich a cross section of the workpiece W is displayed and a parametersetting region 212. In the parameter setting region 212, a plurality ofparameters for setting the first contact target position P1 can be set.For example, the number of measurement points in the XY directions canbe set as a horizontal-direction parameter. In the present example, thenumber of measurement points in the XY directions is two as illustratedin FIG. 21 , and thus, the number of measurement points in the XYdirections is set to two, but the number of measurement points is notlimited thereto. As many measurement points as the set number ofmeasurement points are displayed on the display section 4. The number ofmeasurement points is the number of contact target positions of thetouch probe 80 to be arranged.

The setting section 3 g can set a position in the XY directions on theworkpiece image at the time of setting the first contact target positionP1. For example, the position of the first contact target position P1 inthe XY directions is set by moving the first contact target position P1on the workpiece image using the mouse 6 or the like. Further, theposition of the first contact target position P1 in the XY directionscan be arbitrarily set by inputting a separation distance from thereference position in each of the X direction and the Y directionseparately using the keyboard 5 or the like, for example. Furthermore, aheight position of the first contact target position P1 in the Zdirection can be set in the same manner.

The horizontal-direction parameter may include a setting parameter in ameasurement direction. The measurement direction is an approachdirection of the touch probe 80 toward the contact target position. Themeasurement direction illustrated in FIG. 23 is set as indicated by anarrow, and from right to left, but there is a case where it is desiredto set the opposite direction depending on the workpiece W. In such acase, the user checks “reverse direction” to select the reversedirection. This operation is set by the setting section 3 g and thenstored in the storage section 7 as the approach direction.

Further, the approach direction includes a first approach direction inwhich the touch probe 80 is moved from above to approach the workpiece Wand a second approach direction in which the touch probe 80 is made toapproach the inclined surface S3 of the workpiece W in the normaldirection, and the approach directions can be arbitrarily selected bythe user.

As vertical-direction parameters, the number of measurement points, astart margin, and a measurement range in the Z direction can be set. Inthe present example, the number of measurement points in the Z directionis two. The start margin is a dimension in the Z direction from theupper surface S2 of the workpiece W to the upper first contact targetposition P1. The measurement range is a dimension from the upper firstcontact target position P1 to the lower first contact target positionP1.

In the parameter setting region 212, parameters related to a scan linecan also be set. The scan line can also be defined as a path for movingthe touch probe 80 from a position not in contact with the workpiece Wto a position in contact with the workpiece W. The parameters related tothe scan line is path information of the touch probe 80 when the touchprobe 80 is caused to approach the workpiece W, and an approach path ofthe touch probe 80 to the contact target position can be the scan line.The scan line may be straight or bent.

A start position (start point) of the scan line is the operation startposition of the touch probe 80, and any distance in the horizontaldirection from an edge position of the side surface S1 of the workpieceW that the start position is to have can be set to a specific dimension.Further, any distance from the edge position of the side surface S1 ofthe workpiece W toward the inside of the cross section of the workpieceW that an end position of the scan line is to have can be set to aspecific dimension. Even if the scan line reaches the inside of thecross section of the workpiece W, scanning is automatically stopped whenthe touch probe 80 comes into contact with the workpiece W.

A plurality of the second contact target positions P2 can also be setbased on the absolute coordinates, and can be set to be spaced apartfrom each other in the X direction and the Y direction as illustrated inFIG. 21 . Parameters of the second contact target position P2 aredifferent from the parameters of the first contact target position P1,and the number of measurement points in the X direction and the numberof measurement points in the Y direction are set. Setting ofvertical-direction parameters is omitted. The setting section 3 gextracts and sets, on the workpiece image, a line that is a boundarybetween the upper surface S2 and the inclined surface S3 of theworkpiece W as a second edge measurement element (straight edgeelement), but the second edge measurement element (a part surrounded bya frame line 202) and the second contact target position P2 are notassociated with each other.

A plurality of the third contact target positions P3 can also be setbased on the absolute coordinates, can be set to be spaced apart fromeach other in the circumferential direction of the hole H1, and can beset to be spaced apart from each other in the Z direction. In the caseof the hole H1, a position close to a central axis from the innersurface of the hole H1 in plan view is set as a start position. Theapproach direction is a direction from a position close to the centralaxis from the inner surface of the hole H1 toward the inner surface ofthe hole H1, and this direction can also be set by the user interface asillustrated in FIG. 23 . Further, in the case of the hole H1,measurement points are arranged side by side in the circumferentialdirection, and the number of the measurement points can also be set.Parameters of the third contact target position P3 can be set similarlyto the parameters of the first contact target position P1.

The setting section 3 g extracts and sets a peripheral edge portion ofthe hole H1 as a third edge measurement element (circular edge element)on the workpiece image. The setting section 3 g sets the third contacttarget position P3 in association with the extracted third edgemeasurement element (part surrounded by a frame line 203). When theworkpiece W has a cylindrical portion, a measurement point of thecylindrical portion can be set in the same manner.

A plurality of the fourth contact target positions P4 can also be setbased on the absolute coordinates. FIG. 24 illustrates the userinterface screen 210 for setting the contact target position withrespect to an inclined surface. The horizontal-direction parameters ofthe parameter setting region 212 are similar to those at the time ofsetting the first contact target position P1, but has a difference insetting of tilt-direction parameters. As the tilt-direction parameters,the number of measurement points, a start margin, and a measurementrange in a tilt direction can be set. The start margin is a dimension ina direction along the inclined surface S3 from the second edgemeasurement element to the upper fourth contact target position P4illustrated in FIG. 21 . The measurement range is a dimension from theupper fourth contact target position P4 to the lower fourth contacttarget position P4. Further, a tilt angle α of the inclined surface S3can also be set. The tilt angle α of the inclined surface S3 is angleinformation near the contact target position of the touch probe 80, andthe setting section 3 g can also receive an input of the tilt angle α.Further, the setting section 3 g sets the fourth contact target positionP4 in association with the above-described second edge measurementelement (the part surrounded by the frame line 202 in FIG. 21 ). Varioustypes of setting information set as described above are stored in thestorage section 7.

At the time of measurement setting, a measurement range in whichdimension measurement is performed can also be set. For example, when itis desired to measure only the upper surface S2 of the workpiece W, theuser sets a measurement range so as to surround only the upper surfaceS2 on the workpiece image displayed on the display section 4. Thereceiving section 3 e is configured to be capable of receiving thesetting of the measurement range performed by the user. Settinginformation of the measurement range received by the receiving section 3e is also stored in the storage section 7.

Next, details in step SC10 (measurement using the non-contactdisplacement meter 70) of the flowchart illustrated in FIG. 16 areillustrated in a flowchart illustrated in FIG. 25 . In step SG1 afterthe start, parameters for non-contact displacement measurement are set.Thereafter, the flow proceeds to step SG2, and the control section 3 dreceives designation of a height measurement site on the workpieceimage. In step SG2, a position in the XY directions is designated. Forexample, the user may confirm a desired measurement site and designatethe measurement site using the mouse 6 or the like while viewing theworkpiece image displayed on the display section 4, or may inputposition designation information, such as coordinates, as numericalvalues to designate a measurement site. A plurality of measurement sitescan be designated.

The flow proceeds to step SG3 after the designation of the measurementsite, and the control section 3 d controls the stage 21 such that themeasurement site designated in step SG2 is irradiated with measurementlight of the non-contact displacement meter 70. Specifically, thecontrol section 3 d controls the Z-direction driving section 25 and theXY-direction driving section 23 to make a focal point of the non-contactdisplacement meter 70 coincide with the measurement site designated instep SG2. Then, in step SG4, the measurement light is emitted to executemeasurement. In step SG5, the displacement measuring section 3 ccalculates a dimension. At this time, an average process, which will bedescribed later, may be executed.

After step SC10 in the flowchart of FIG. 16 , the flow proceeds to stepSC11. In step SC11, a measurement tool is set. For example, a tool formeasuring a separation dimension between lines, a tool for measuring adiameter, a tool for measuring an angle, and the like can be displayedin a list form on the display section 4 such that the user can select adesired tool. The measurement tool selected by the user is saved.

In step SC12, a measurement result by the measurement tool set in stepSC11 is superimposed and displayed on the workpiece image on the displaysection 4. When a color image is acquired, the measurement result issuperimposed and displayed on the color image. Setting of a range inwhich the measurement result is displayed in a superimposed manner canalso be received in advance by the receiving section 3 e. At the time ofmeasurement setting, for example, if the user designates a range inwhich the measurement result is desired to be superimposed and displayedon the color image displayed on the display section 4, the range isreceived by the receiving section 3 e and then stored in the storagesection 7. At the time of measurement execution, the designated range isread from the storage section 7, and the measurement result is displayedin a superimposed manner only within the designated range. Note that themeasurement result can also be displayed in a moving image when alive-view image is acquired.

Further, in step SC13, for example, when a measurement result by theimage measuring section 3 a is acquired, the measurement result of theimage measuring section 3 a is superimposed and displayed on thebird's-eye view image generated by the front camera 48. In step SC13,geometric elements 221 and 222 corresponding to the measurement resultof the image measuring section 3 a can also be displayed on thebird's-eye view image, for example, as illustrated in FIG. 26 . FIG. 26is another example of a user interface screen 220 for displaying thegeometric elements 221 and 222 (indicated by thick lines) on the displaysection 4, and a workpiece image and the geometric elements 221 and 222corresponding to shapes of measurement elements of the workpiece imageare displayed in a superimposed manner. The geometric elements 221 and222 may have a rectangular shape and the like other than a straight lineand a circle, and only need to have shapes corresponding to themeasurement elements. The geometric elements 221 and 222 are set as edgemeasurement elements by the setting section 3 g, and include a straightedge, a circular edge, a rectangular edge, and the like.

Arrangement positions and the number of contact target positions of thetouch probe 80 can be made to correspond to each of the measurementelements. For example, the geometric element 221 and the geometricelement 222 can be associated, respectively, with different positions aspositions at which the contact target positions are arranged, and can beassociated, respectively, with different numbers of contact targetpositions. The correspondence relationship between a shape type or asize of the measurement element and the arrangement positions and thenumber of contact target positions of the touch probe 80 with respect tothe measurement element can be stored in the storage section 7. Notethat the shape type, size, and the like of the geometric element canalso be set on the bird's-eye view image.

The bird's-eye view image is an image generated by the front camera 48,whereas the workpiece image from which the geometric elements 221 and222 are extracted is an image generated by the imaging section 50different from the front camera 48, and thus, there is a possibilitythat a deviation occurs if the geometric element is superimposed anddisplayed on the bird's-eye view image without correction. However, thepresent example is configured such that it is possible to execute acorrection process of correcting the deviation of the geometric elementwith respect to the bird's-eye view image before measurement. Examplesof the deviation of the geometric element include a deviation due tooptical characteristics of the camera and the lens, a deviation of thecamera, and the like. The correction process may be performed at thetime of shipment of the image measurement apparatus 1 from a factory, ormay be performed after the shipment. The correction process may beperformed by any method, and an example thereof will be described below.

In the correction process, for example, a workpiece for correction (notillustrated) having a dot chart or the like is prepared and placed onthe stage 21. An image of the workpiece for correction on the stage 21is captured by the imaging section 50, and center coordinates of each ofdots are detected. Further, the front camera 48 also captures an imageof the workpiece for correction on the stage 21, and detects centercoordinates of each of the dots. A correction table is generated as aninternal parameter so as to enable transformation of the centercoordinates detected based on the image of the imaging section 50 andthe center coordinates detected based on the image of the front camera48. Instead of the correction table, a transformation function may beused. Thereafter, the correction table is applied to the image capturedby the imaging section 50 to perform transformation into projectioncoordinates.

The correction process includes, for example, an external parameterdetection process. That is, an image of the workpiece for correction onthe stage 21 is captured by the imaging section 50, andthree-dimensional coordinates of the center of each of dots aredetected. Center coordinates of each of the dots in the projectioncoordinates of the image of the front camera 48 are obtained using theinternal parameter. A transformation matrix of these correspondingimages is obtained. Further, positions and postures of the imagingsection 50 and the front camera 48 are defined in a three-dimensionalspace. The transformation matrix between the center coordinates detectedbased on the image of imaging section 50 for the detected dot and thecenter coordinates detected based on the image of front camera 48 isobtained.

In step SC13 of the flowchart illustrated in FIG. 16 , measurementresults and the geometric elements 231 and 232 may be superimposed anddisplayed on a user interface screen 230 capable of three-dimensionallydisplaying the workpiece W as illustrated in FIG. 27 .

In step SC14, it is determined if there is no other measurement element.If there is any other measurement element, the flow returns to step SC7.If there is no other measurement element, the flow proceeds to stepSC15. In step SC15, a pattern search is set. For example, as illustratedin FIG. 21 , the alignment mark M, which is the characteristic pattern,can be set as a search target. In this case, the user can generate theframe line 200 surrounding the alignment mark M, and can designate aregion in the frame line 200 as a search region.

In step SC16, pieces of setting information set in the respectiveprocesses illustrated in this flowchart are stored in the storagesection 7. That is, the characteristic pattern (characteristic amountinformation) set by the setting section 3 g, a relative positionalrelationship between the first and second contact target positions P1and P2 with respect to the characteristic pattern, and the like arestored. Further, for example, a fixed positional relationship betweenthe imaging section 50 and the touch probe 80 or the like is also storedin the storage section 7. The fixed positional relationship is arelative positional relationship of the touch probe 80 with respect tothe imaging section 50, and may be, for example, a relationshipindicated by coordinate information, or a relationship indicated by arelative separation distance, separation direction, and the like.

(Measurement Operation of Touch Probe)

Next, details of the measurement operation of the touch probe 80, thatis, details of step SF8 of the flowchart illustrated in FIG. 19 will bedescribed based on a flowchart illustrated in FIG. 28 . After the start,the control section 3 d controls the Z-direction driving section 25 tomove the measurement execution section 24 upward to the retractedposition, and then mounts the desired stylus 83 to the touch probe 80using the changer mechanism 100 although not illustrated in this flow.Thereafter, the flow proceeds to step SH1, and the contact portion 83 bof the touch probe 80 is relatively moved to the start point of the scanline set on the user interface screen 210 for setting illustrated inFIG. 23 . Specifically, the control section 3 d controls theXY-direction driving section 23 to move the stage 21 in the XYdirections, and causes XY coordinates of the start point of the scanline to coincide with XY coordinates of the contact portion 83 b of thetouch probe 80. Thereafter, the control section 3 d controls theZ-direction driving section 25 to lower the measurement executionsection 24, and places the contact portion 83 b of the touch probe 80 atthe start point of the scan line.

In step SF12, the control section 3 d controls the XY-direction drivingsection 23 and the Z-direction driving section 25 to relatively move thecontact portion 83 b of the touch probe 80 in a direction of the scanline (an arrow direction in FIGS. 23 and 24 ). In step SF13, it isdetermined whether or not the touch probe 80 has detected contact. Ifthe touch probe 80 does not detect any contact, the contact portion 83 bof the touch probe 80 is kept relatively moved in the direction of thescan line. When the contact portion 83 b of the touch probe 80 comesinto contact with the workpiece W, the movement is stopped, and it isdetermined as YES in step SH3, and the flow proceeds to step SH4.

In step SH4, the coordinate measuring section 3 b acquires X, Y, and Zcoordinates when the contact portion 83 b of the touch probe 80 comesinto contact with the workpiece W, and uses the X, Y, and Z coordinatesas measurement values. In step SH5, the control section 3 d controls theXY-direction driving section 23 and the Z-direction driving section 25to return the contact portion 83 b of the touch probe 80 to the startpoint of the scan line. In step SH6, it is determined whether or not themeasurement has been completed for all scan lines. When the measurementhas been completed for all the scan lines, the flow proceeds to stepSH7, and the control section 3 d controls the Z-direction drivingsection 25 to move the measurement execution section 24 upward to theretracted position. Thereafter, the stylus 83 is detached by the changermechanism 100 and stored in the retracted position as necessary.

In a case where it is determined as NO in step SH6 and there is a scanline for which measurement has not been completed, the flow proceeds tostep SH8 to determine a retraction method. When the retraction method isa method of performing retraction in the Z direction, the flow proceedsto step SE19, and the control section 3 d controls the Z-directiondriving section 25 to move the measurement execution section 24 upwardto the retracted position. In step SH10, the control section 3 dcontrols the XY-direction driving section 23 to relatively move thecontact portion 83 b of the touch probe 80 to the start point (X, Y) ofthe scan line. Thereafter, in step SH11, the control section 3 dcontrols the Z-direction driving section 25 to relatively move thecontact portion 83 b of the touch probe 80 to the start point (Z) of thescan line.

In a case where the retraction method is a polygon retraction method,the flow proceeds to step SH12. In step SH12, the control section 3 dcontrols the XY-direction driving section 23 to relatively move thecenter of the contact portion 83 b of the touch probe 80 to the startpoint (X, Y) of the scan line so as to form a polygon along thecircumferential direction of the measurement element.

When no retraction is performed, the flow proceeds to step SH13, and thecontrol section 3 d controls the XY-direction driving section 23 torelatively move the contact portion 83 b of the touch probe 80 to thestart point (X, Y) of the scan line.

(At Time of Measurement Execution)

FIGS. 29A and 29B are flowcharts illustrating an example of a procedureat the time of measurement execution of the image measurement apparatus1. In step SI1 after the start, the setting information stored in thestorage section 7 is read. For example, the characteristic pattern, thesearch region, the relative positional relationship between the firstand second contact target positions P1 and P2 with respect to thecharacteristic pattern, the fixed positional relationship between theimaging section 50 and the touch probe 80, and the like are read. Due toprovision of this step, it is unnecessary for the user to move the touchprobe 80 to set reference coordinates each time the workpiece W isplaced on the stage 21, thereby simplifying measurement work.

Further, in step SI1, the position of the measurement element on theworkpiece image and the shape type or size of the measurement elementare read from the storage section 7. Furthermore, the correspondencerelationship between the shape type or size of the measurement elementand the arrangement positions and the number of contact target positionsof the touch probe 80 with respect to the measurement element is alsoread from the storage section 7.

In step SI2, the plan-view image is acquired by causing the imagingsection 50 to capture the stage 21 from above, and is displayed on thedisplay section 4. In step SI2, the connected image may be displayed, orthe bird's-eye view image captured by the front camera 48 may bedisplayed. Further, the imaging section 50 may acquire the connectedimage using any one imaging element of the high-magnification-sideimaging element 55 and the low-magnification-side imaging element 56, ormay acquire the connected images using both the imaging elements,respectively. As described above, since the configuration of thebifurcated optical system using the beam splitter 52 is adopted in thepresent embodiment, the high-magnification image and thelow-magnification image may be simultaneously acquired, and a firstconnected image obtained by connecting the high-magnification images anda second connected image obtained by connecting the low-magnificationimages may be acquired.

In step SI3, it is determined whether or not to execute ghost display.For example, if the user selects “Execute ghost display” at the time ofmeasurement setting, it is determined as YES in step SI3, the flowproceeds to step SI4, and the control section 3 d executes the ghostdisplay of the search region on the display section 4 to guide theworkpiece W to be placed at an appropriate position on the stage 21. Theghost display is to display the search region set in advance at the timeof measurement setting to be superimposed on the plan-view image, and,for example, to display the search region to be lighter than theplan-view image so as not to interfere with recognition of the plan-viewimage. If the user selects “Do not execute ghost display” at the time ofmeasurement setting, it is determined as NO in step SI3, and the flowproceeds to step SI5. The ghost display may be executed on the connectedimage, the bird's-eye view image, or the like.

In step SI5, it is determined whether or not to designate the searchregion. That is, when the user designates the search region of thecharacteristic pattern at the time of measurement execution, it isdetermined as YES in step SI5, and the flow proceeds to step SI6. On theother hand, when the user does not designate the search region, the flowproceeds to step SI7. The search region is designated as the userperforms an operation of surrounding a specific region by operating themouse 6 or the like on any image among, for example, the plan-viewimage, the connected image, the bird's-eye view image, and the like. Atthis time, for example, when the bird's-eye view image acquired bycapturing the entire workpiece W using the imaging section 50 (which maybe the stage cameras 46 and 47 or the front camera 48) is displayed onthe display section 4, the designation of the search region by the useron the bird's-eye view image displayed on the display section 4 can bereceived. Note that the search range can be more easily designated byusing the imaging section 50 or the stage cameras 46 and 47 capturing animage from directly above than the front camera 48 capturing an imageobliquely.

In step SI7, it is determined whether or not the measurement startbutton 2 a has been pressed. Steps SI2 to SI7 are repeated until themeasurement start button 2 a is pressed, and the flow proceeds to stepSI8 at a timing at which the measurement start button 2 a is pressed. Instep SI8, it is determined whether or not to display the bird's-eye viewimage on the display section 4. If the user selects “Display bird's-eyeview image” at the time of measurement setting, it is determined as YESin step SI8, the flow proceeds to step SI9, and the control section 3 dcauses the display section 4 to display the bird's-eye view imagecaptured by the front camera 48. If the user selects “Do not displaybird's-eye view image” at the time of measurement setting, it isdetermined as NO in step SI8, and the flow proceeds to step SI10.

In step SI10, it is determined whether or not to generate a color image.If the user selects “Generate color image” at the time of measurementsetting, it is determined as YES in step SI10, and the flow proceeds tostep SI12. In step SI12, a color image of the workpiece W (a workpieceimage newly generated for measurement) is generated by processingsimilar to that in step SC5 illustrated in FIG. 16 . On the other hand,if the user selects “Do not generate color image” at the time ofmeasurement setting, it is determined as NO in step SI10, and the flowproceeds to step SI11. In step SI11, a grayscale image (a workpieceimage newly generated for measurement) of the workpiece W is generatedby processing similar to that in step SC4 illustrated in FIG. 16 .

Next, the flow proceeds to step SI13 in FIG. 29B. In step SI13, apattern search target image is acquired. For example, the controlsection 3 d can acquire the color image of the workpiece W newlygenerated for measurement in step SI11 or the grayscale image of theworkpiece W newly generated for measurement in step SI12 as the patternsearch target image. After acquiring the pattern search target image,the flow proceeds to step SI14, and the control section 3 d specifies aposition and a posture of a characteristic pattern from the workpieceimage newly generated for measurement. At this time, when the searchregion is designated by the user in step SIG, the position and postureof the characteristic pattern are specified by narrowing down to thedesignated search region. As a result, a processing speed is improved.

Further, in a case where a connected image is set as the workpieceimage, the control section 3 d controls the XY-direction driving section23 to move the stage 21 in the XY directions until the workpiece Wenters the visual field range of the imaging section 50. When theworkpiece W enters the visual field range, the imaging section 50captures an image of the workpiece W that has entered the visual fieldrange. Thereafter, the stage 21 is moved in the XY directions such thatanother part of the workpiece W enters the visual field range, and then,the imaging section 50 captures an image of the another part of theworkpiece W that has entered the visual field range. The connected imageobtained by connecting the plurality of images acquired in this manneris used as the workpiece image, and the position and posture of thecharacteristic pattern are specified from the connected image. In thiscase as well, when the search region is designated by the user, theposition and posture of the characteristic pattern are specified bynarrowing down to the designated search region.

Thereafter, the flow proceeds to step SI15. In step SI15, the controlsection 3 d specifies the first contact target position P1 and thesecond contact target position P2 for measurement based on the relativepositional relationship between the first and second contact targetpositions P1 and P2 with respect to the position and posture of theworkpiece W and the characteristic pattern specified in step SI14, andthe fixed positional relationship between the imaging section 50 and thetouch probe 80. For example, when at least one of the position and theposture of the workpiece W based on the workpiece image newly generatedat the time of measurement execution is different from the position orthe posture of the workpiece W used at the time of measurement setting,the position or the posture of the workpiece W can be corrected based onthe position and the posture of the workpiece W specified in step SI14.A position is specified by an X coordinate and a Y coordinate, and aposture is specified by a rotation angle around the X axis and arotation angle around the Y axis. Correcting a position can be referredto as position correction, and correcting a posture can be referred toas posture correction, but these may be collectively referred to asposition correction.

When the relative positional relationship between the first and secondcontact target positions P1 and P2 with respect to the characteristicpattern is used at the time of position correction, the first and secondcontact target positions P1 and P2 can be specified as positions similarto those at the time of measurement setting even after the correction.

Further, the control section 3 d can execute a pattern search on theworkpiece image newly generated for measurement by the imaging section50 to specify an edge measurement element, extract an edge from thespecified edge measurement element, and specify the first contact targetposition P1 and the second contact target position P2 based on theextracted edge. The third contact target position P3 and the fourthcontact target position P4 illustrated in FIG. 21 can also be specifiedin the same manner. Since the fourth contact target position P4 is theposition specified on the inclined surface S3, the fourth contact targetposition P4 can be specified using the tilt angle α of the inclinedsurface S3 at the time of specifying the fourth contact target positionP4. Since the tilt angle α is known, the normal direction of theinclined surface S3 can be estimated. As a result, the fourth contacttarget position P4 can be specified as a position where the touch probe80 is brought into contact with the inclined surface S3 of the workpieceW in the normal direction of the inclined surface S3.

After the contact target position is specified, the flow proceeds tostep SI16. In step SI16, when there are a plurality of measurementsites, the order of the measurement sites is determined.

Steps SI17 to SI20 are the same as Steps SC7 to SC10 in the flowchartillustrated in FIG. 16 . For example, when image measurement isperformed in step SI18, the measurement is performed only within themeasurement range received by the receiving section 3 e. As a result,the measurement accuracy is improved.

Further, for example, in step SI19, the control section 3 d controls theXY-direction driving section 23 such that the touch probe 80 comes intocontact with the side surface of the workpiece W with the first contacttarget position P1 for measurement specified in step SI15 as areference. Further, the control section 3 d controls the Z-directiondriving section 25 such that the touch probe 80 comes into contact withthe upper surface of the workpiece W with the second contact targetposition P2 for measurement specified in step SI15 as a reference. Atthis time, the touch probe 80 is relatively moved along the scan lineset at the time of measurement setting, and the number of measurementpoints, the start margin, the start position, the end position, theapproach direction, and the like are reflected.

When the touch probe 80 is to be relatively moved with respect to theworkpiece W, the control section 3 d controls the Z-direction drivingsection 25 and the XY-direction driving section 23 such that the touchprobe moves along the approach direction set in FIG. 23 . At this time,a relative movement speed is set to a first speed until the touch probe80 comes into contact with the workpiece W, and the touch probe 80 isreturned from a contact position by a predetermined distance when thecontact is detected. Thereafter, the touch probe 80 is relatively movedat a second speed lower than the first speed until coming into contactwith the workpiece W, and a measurement result is output based on acontact position at the second speed. This enables precise measurement.

Further, when the touch probe 80 is to be brought into contact with theinclined surface of the workpiece W, the touch probe 80 is brought closeto the inclined surface of the workpiece W at the first speed, and therelative movement speed is set to the second speed at a time point whena distance between the touch probe 80 and the inclined surface of theworkpiece W becomes a predetermined distance. Then, a measurement resultis output based on a contact position at the second speed.

Further, in step S1, the control section 3 d reads the position of themeasurement element on the workpiece image, the shape type or size ofthe measurement element, and the correspondence relationship between theshape type or size of the measurement element and the arrangementpositions and the number of contact target positions of the touch probe80 with respect to the measurement element. Therefore, the controlsection 3 d can specify a plurality of contact target positions of thetouch probe 80 based on the position of the measurement element on theworkpiece image, the shape type or size of the measurement element, andthe correspondence relationship, and control the XY-direction drivingsection 23 and the Z-direction driving section 25 such that the touchprobe 80 sequentially moves to the plurality of specified contact targetpositions. Since the plurality of contact target positions of the touchprobe 80 are automatically specified based on the information at thetime of measurement setting, and the XY-direction driving section 23 andthe Z-direction driving section 25 are automatically controlled in thismanner, the measurement work by the user is simplified.

In step SI20, non-contact height measurement using the non-contactdisplacement meter 70 is performed. At this time, there is a case whereheight measurement is performed a plurality of times by the non-contactdisplacement meter 70, and an averaging process of averaging a pluralityof acquired height measurement values is executed. A specific examplewill be described with reference to a flowchart illustrated in FIG. 30 .

In step SJ1 after the start, the control section 3 d drives theZ-direction driving section 25 to move the measurement execution section24 such that a focal point of the non-contact displacement meter 70matches a measurement site. In step SJ2, it is determined whether or nota measurement value is readable by the non-contact displacement meter70. When the measurement value is not readable, the flow proceeds tostep SJ3 to perform a coarse search, that is, the measurement executionsection 24 is moved to a position where the measurement value isreadable by the non-contact displacement meter 70. When the measurementvalue is readable in step SJ2, the flow proceeds to step SJ3 to executea refine search. In the refine search, the measurement execution section24 is moved to perform focus adjustment such that the measurement valueof the non-contact displacement meter 70 becomes approximately zero.

In step SJ5, it is determined whether or not the measurement value ofthe non-contact displacement meter 70 is less than a convergencedetermination value. The convergence determination value can be set to,for example, about 0.2 mm, but is not limited thereto. When it isdetermined as NO in step SJ5 and the measurement value of thenon-contact displacement meter 70 is equal to or more than theconvergence determination value, the flow proceeds to step SJ6 todetermine whether or not the number of feedback iterations is exceeded.The number of feedback iterations can be set to, for example, five, butis not limited thereto. The flow proceeds to step SJ4 when the number offeedback iterations is not exceeded, and proceeds to step SJ7 when thenumber of feedback iterations is exceeded. In step SJ7, it is determinedwhether automatic adjustment is turned OFF. When the automaticadjustment is turned ON, the flow proceeds to step SJ8, and it isdetermined whether or not a second peak of a light reception waveform ofthe non-contact displacement meter 70 has been acquired. When the secondpeak has been acquired, the flow proceeds to step SJ11 to set atransparent body mode since the workpiece W is estimated to be atransparent body. When the second peak has not been acquired, the flowproceeds to step SJ12 to set a non-transparent body mode since theworkpiece W is estimated to be a non-transparent body.

Thereafter, the flow proceeds to step SJ13. In step SJ13, a diameter ofa rose curve, used in the averaging process of the measurement values,during scanning is set to a small diameter. In step SJ14, the controlsection 3 d controls the stage 21 such that the focal point of thenon-contact displacement meter 70 becomes a locus drawing the rose curveon the surface of the workpiece W. A figure formed by the rose curve inthe averaging process is a point-symmetric and line-symmetric figure.The center of the rose curve is set as a measurement target point. Thediameter of the rose curve may be selectable by the user from amongpredetermined values such as 0.25 mm, 0.5 mm, and 1 mm.

Whether or not to execute the averaging process may be selectable by theuser. For example, it is also possible to adopt a configuration in whichselection of execution or non-execution of the averaging process by theuser is received on a user interface such that the averaging process isexecuted when the execution is selected, and the averaging process isnot executed when the non-execution is selected.

In step SJ14, it is further determined whether or not a measurementvalue variance during scanning of the rose curve is smaller than anautomatic adjustment threshold. The automatic adjustment threshold canbe set to, for example, about 0.005 mm, but is not limited thereto. Whenthe measurement value variance during the scanning of the rose curve isequal to or larger than the automatic adjustment threshold, the rosecurve is set to ON (the averaging process is executed). On the otherhand, when the measurement value variance during the scanning of therose curve is smaller than the automatic adjustment threshold, thehighly accurate measurement values can be acquired without executing theaveraging process, and thus, the rose curve is set to OFF (the averagingprocess is not executed).

Next, the flow proceeds to step SJ17 to execute the measurement, andthen, proceeds to step SJ18 to calculate a dimension. At the time ofmeasurement execution, the scanning of the rose curve is executed tohold the measurement values at the plurality of points. During thedimension calculation, the averaging process of the measurement valuesat the plurality of points is executed to determine an output value.

After the measurement is executed as described above, the flow proceedsto step SI21 in FIG. 29B. In step SI21, it is determined whether or notthe measurement has been completed for all the measurement sites. Theflow proceeds to step SI17 when there remains a measurement site, andproceeds to steps SI22 and SI23 when the measurement has been completedfor all the measurement sites. In steps SI22 and SI23, the measurementresult is superimposed and displayed on the workpiece image as in stepsSC12 and SC13 of the flowchart illustrated in FIG. 16 .

In the measurement by the non-contact displacement meter 70, the controlsection 3 d may execute an extraction process of extracting an edgemeasurement element to be used in image measurement on the workpieceimage. When the edge measurement element is successfully extracted inthis extraction process, the control section 3 d executes the imagemeasurement and the height measurement by the non-contact displacementmeter 70.

Further, in the measurement by the non-contact displacement meter 70,the control section 3 d may move the stage 21 in a direction orthogonalto the imaging axis of the imaging section 50 such that the focal pointof the non-contact displacement meter 70 coincides with the measurementsite, then execute the height measurement by the non-contactdisplacement meter 70 to determine whether or not the height measurementvalue is acquired, and control the Z-direction driving section 25 tomove the non-contact displacement meter 70 along the imaging axis untilthe height measurement value is acquired in a case where the heightmeasurement value is not acquired. Therefore, the non-contactdisplacement meter 70 is moved in the imaging-axis direction togetherwith the imaging section 50 by using the Z-direction driving section 25that adjusts the focal position of the imaging section 50, and thus, itis possible to shorten a measurement time in a case where highlyaccurate height measurement is performed using the non-contactdisplacement meter 70.

(Indicator)

As illustrated in FIG. 6 , the apparatus body 2 is provided with anindicator 2 c. The indicator 2 c is provided on a surface of theapparatus body 2 facing the user, and is controlled by the control unit3. The indicator 2 c indicates the above-described measurement result,and includes, for example, a light emitting section, a display section,and the like. The control unit 3 controls the indicator 2 c such thatdisplay differs between a case where the measurement result satisfies apredetermined condition and a case where the measurement result does notsatisfy the predetermined condition. The predetermined condition is setin advance by the user and stored in the storage section 7 or the like.For example, red or the like is displayed as defective if themeasurement result is equal to or more than a certain value, and greenor the like is displayed as non-defective the measurement result is lessthan the certain value.

MODIFIED EXAMPLES

FIG. 31 illustrates a first modified example in which thehigh-magnification-side imaging element 55 and thelow-magnification-side imaging element 56 of the imaging section 50 arethree-channel imaging elements. That is, since thehigh-magnification-side imaging element 55 and thelow-magnification-side imaging element 56 are configured usingthree-channel imaging elements including RGB, the ring illumination 45can generate a color workpiece image by projecting only one color ofwhite light.

In the first modified example, the control unit 3 includes a converter 3h. The converter 3 h is a part that converts a color workpiece imagegenerated by the imaging section 50 into a grayscale workpiece image,and this conversion can be performed by a conventionally knowntechnique. The image measuring section 3 a is configured to measure adimension of the workpiece W based on the grayscale workpiece imageconverted by the converter 3 h.

Further, the color information generating section 3 f generates colorinformation of the workpiece W based on the color workpiece imagegenerated by the imaging section 50. The control section 3 d generates acolor image obtained by adding the color information of the workpiece Wgenerated by the color information generating section 3 f to thegrayscale workpiece image converted by the converter 3 h. As a result,the display section 4 can display the color image, obtained by addingthe color information of the workpiece generated by the colorinformation generating section 3 f to the grayscale workpiece imageconverted by the converter 3 h, and display a result of the dimensionmeasurement obtained by the image measuring section 3 a on the colorimage in a superimposed manner.

Next, a second modified example illustrated in FIG. 32 will bedescribed. The second modified example includes: a first imaging section50A that includes a single-channel imaging element and receivesdetection light to generate a grayscale workpiece image; and a secondimaging section 50B that includes a three-channel imaging elementincluding RGB and receives detection light to generate a color workpieceimage. The first imaging section 50A includes the single-channelhigh-magnification-side imaging element 55 and the single-channellow-magnification-side imaging element 56. The image measuring section 3a is configured to measure a dimension of the workpiece W based on theworkpiece image generated by the first imaging section 50A.

The color information generating section 3 f generates color informationof the workpiece W based on a workpiece image generated by the secondimaging section 50B. The control section 3 d generates a color imageobtained by adding the color information of the workpiece W generated bythe color information generating section 3 f to the grayscale workpieceimage generated by the first imaging section 50A. The display section 4displays the color image generated by the control section 3 d andsuperimposes and displays a result of the dimension measurement in theimage measuring section 3 a on the color image.

The above-described embodiment is merely an example in all respects, andshould not be construed as limiting. Further, all modifications andchanges belonging to the equivalent range of the claims fall within thescope of the present invention.

As described above, the disclosure can be used to measure thethree-dimensional coordinates of the workpiece placed on the stage.

What is claimed is:
 1. An image measurement apparatus comprising: astage on which a workpiece is placed; a light projecting section whichirradiates the workpiece on the stage with detection light; an imagingsection which receives the detection light and generates a workpieceimage; a touch probe which outputs a contact signal when the touch probecomes into contact with the workpiece on the stage; a driving sectionwhich moves at least one of the stage and the touch probe with respectto another to bring the touch probe into contact with the workpieceplaced on the stage; a display section which displays the workpieceimage generated by the imaging section during measurement setting; asetting section which sets, on the workpiece image displayed on thedisplay section, a first contact target position serving as a referencefor bringing the touch probe into contact with a side surface of theworkpiece in XY directions, a second contact target position serving asa reference for bringing the touch probe into contact with an uppersurface of the workpiece in a Z direction, and a characteristic patternfor specifying a position and a posture of the workpiece duringmeasurement execution in association with each other when a direction ofan imaging axis of the imaging section is defined as a Z axis, adirection orthogonal to the Z axis is defined as an X axis, and adirection orthogonal to the Z axis and orthogonal to the X axis isdefined as a Y axis; a storage section which stores the characteristicpattern set by the setting section, a relative positional relationshipbetween the first and second contact target positions with respect tothe characteristic pattern, and a fixed positional relationship betweenthe imaging section and the touch probe; a control section whichspecifies a position and a posture of the characteristic pattern storedin the storage section from a workpiece image newly generated formeasurement by the imaging section during the measurement execution,specifies first and second contact target positions for measurementbased on the specified position and posture, and the relative positionalrelationship and the fixed positional relationship stored in the storagesection, controls the driving section to bring the touch probe intocontact with the side surface of the workpiece with the specified firstcontact target position for measurement as a reference, and controls thedriving section to bring the touch probe into contact with the uppersurface of the workpiece with the specified second contact targetposition for measurement as a reference; and a measuring section whichmeasures three-dimensional coordinates of a contact point at which thetouch probe comes into contact with the workpiece based on the contactsignal output when the touch probe comes into contact with the workpieceby an operation of the driving section controlled by the controlsection.
 2. The image measurement apparatus according to claim 1,wherein the setting section sets the first and second contact targetpositions in association with an edge measurement element extracted onthe workpiece image and used in image measurement.
 3. The imagemeasurement apparatus according to claim 2, wherein the control sectionexecutes a pattern search on the workpiece image newly generated formeasurement by the imaging section to specify the edge measurementelement, extracts an edge from the specified edge measurement element,and specifies the first contact target position based on the extractededge.
 4. The image measurement apparatus according to claim 1, whereinthe setting section sets a position in the XY directions on theworkpiece image when the setting section sets the first contact targetposition, and also sets a height position in the Z direction of thefirst contact target position, and the control section controls thedriving section to bring the touch probe into contact with the sidesurface of the workpiece with a position in the XY directions and aposition in the Z direction of the specified first contact targetposition for measurement as references.
 5. The image measurementapparatus according to claim 1, wherein the setting section sets pathinformation for causing the touch probe to approach the workpiece froman operation start position included in the first contact targetposition.
 6. The image measurement apparatus according to claim 1,further comprising: a base which supports the stage to be movable in ahorizontal direction; and a support section which is connected to thebase and supports the imaging section above the stage, wherein thesetting section sets the first and second contact target positions basedon absolute coordinates in a three-dimensional space surrounded by thestage, the support section, and the imaging section.
 7. The imagemeasurement apparatus according to claim 1, wherein the control sectioncontrols the driving section to move the stage in the XY directionsuntil the workpiece enters a visual field range of the imaging section,controls the imaging section to capture an image of the workpieceentering the visual field range when the workpiece enters the visualfield range, moves the stage in the XY directions to make another partof the workpiece enter the visual field range, then controls the imagingsection to capture an image of the workpiece entering the visual fieldrange, sets a connected image obtained by connecting a plurality of theacquired images as the workpiece image, and specifies the position andthe posture of the characteristic pattern from the workpiece image. 8.The image measurement apparatus according to claim 1, wherein thecontrol section causes the display section to display a bird's-eye viewimage, acquired by capturing a whole of the workpiece using the imagingsection or another imaging section, during the measurement execution,receives designation of a search region performed by a user on thebird's-eye view image displayed on the display section, and specifiesthe position and the posture of the characteristic pattern by narrowingdown to the search region designated by the user.
 9. The imagemeasurement apparatus according to claim 1, wherein the control sectioncauses the display section to display an image acquired by capturing theworkpiece using the imaging section or another imaging section duringthe measurement execution, and performs ghost display of a preset searchregion on the display section to guide the workpiece to be placed at anappropriate position on the stage.
 10. The image measurement apparatusaccording to claim 1, wherein the setting section sets another contacttarget position serving as a reference for bringing the touch probe intocontact with an inclined surface of the workpiece in a directioninclined with respect to the Z axis in association with thecharacteristic pattern, the storage section stores a relative positionalrelationship of the other contact target position with respect to thecharacteristic pattern, and the control section specifies anothercontact target position for measurement based on the specified positionand posture, and the relative positional relationship and the fixedpositional relationship stored in the storage section, and controls thedriving section to bring the touch probe into contact with the inclinedsurface of the workpiece with the specified other contact targetposition for measurement as a reference.
 11. An image measurementapparatus comprising: a stage on which a workpiece is placed; a lightprojecting section which irradiates the workpiece on the stage withdetection light; an imaging section which receives the detection lightand generates a workpiece image; a touch probe which outputs a contactsignal when the touch probe comes into contact with the workpiece on thestage; a driving section which moves at least one of the stage and thetouch probe with respect to another to bring the touch probe intocontact with the workpiece placed on the stage; a display section whichdisplays the workpiece image generated by the imaging section; a settingsection which sets, on the workpiece image displayed on the displaysection, an edge measurement element from which an edge of a sidesurface of the workpiece is to be extracted, a first contact targetposition serving as a reference for bringing the touch probe intocontact with the side surface of the workpiece in XY directions, and acharacteristic pattern for specifying a position and a posture of theworkpiece; a control section which searches for the position and postureof the characteristic pattern set by the setting section from aworkpiece image newly generated for measurement by the imaging sectionto specify the edge measurement element, extracts the edge from thespecified edge measurement element, specifies the first contact targetposition based on the extracted edge, and controls the driving sectionto bring the touch probe into contact with the side surface of theworkpiece with the specified first contact target position as thereference; and a measuring section which measures three-dimensionalcoordinates of a contact point at which the touch probe comes intocontact with the workpiece based on a contact signal output when thetouch probe comes into contact with the workpiece by an operation of thedriving section controlled by the control section.
 12. The imagemeasurement apparatus according to claim 11, wherein the setting sectionsets a scan line which is path information for causing the touch probeto approach the workpiece from an operation start position included inthe first contact target position.
 13. The image measurement apparatusaccording to claim 12, wherein the setting section is capable of settingany distance from an edge position of the side surface of the workpiecein a horizontal direction that a start position of the scan line is tohave, and is capable of setting any distance from the edge position ofthe side surface of the workpiece inward a cross section of theworkpiece that an end position of the scan line is to have.
 14. Theimage measurement apparatus according to claim 11, wherein the settingsection is capable of setting a number of the first contact targetpositions to be arranged, and is capable of setting a position of thefirst contact target position in the XY directions by moving the firstcontact target position displayed on the display section on theworkpiece image.
 15. An image measurement apparatus comprising: a stageon which a workpiece is placed; a light projecting section whichirradiates the workpiece on the stage with detection light; an imagingsection which receives the detection light and generates a workpieceimage; a touch probe which outputs a contact signal when the touch probecomes into contact with the workpiece on the stage; a driving sectionwhich moves at least one of the stage and the touch probe with respectto another to bring the touch probe into contact with the workpieceplaced on the stage; a display section which displays the workpieceimage generated by the imaging section during measurement setting; asetting section capable of setting, on the workpiece image displayed onthe display section, a first contact target position serving as areference for bringing the touch probe into contact with a straight edgeelement of a side surface of the workpiece in XY directions, a secondcontact target position serving as a reference for bringing the touchprobe into contact with an upper surface of the workpiece in a Zdirection, a third contact target position serving as a reference forbringing the touch probe into contact with an arcuate edge element ofthe side surface of the workpiece in the XY directions, a fourth contacttarget position serving as a reference for bringing the touch probe intocontact with an inclined surface of the workpiece in a normal directionof the inclined surface, and a characteristic pattern for specifying aposition and a posture of the workpiece when a direction of an imagingaxis of the imaging section is defined as a Z axis, a directionorthogonal to the Z axis is defined as an X axis, and a directionorthogonal to the Z axis and orthogonal to the X axis is defined as a Yaxis; a control section which specifies a position and a posture of thecharacteristic pattern from a workpiece image newly generated formeasurement by the imaging section, specifies first, second, third, andfourth contact target positions for measurement based on the specifiedposition and posture, controls the driving section to bring the touchprobe into contact with the side surface of the workpiece with thespecified first and third contact target positions for measurement asreferences, controls the driving section to bring the touch probe intocontact with the upper surface of the workpiece with the specifiedsecond contact target position for measurement as a reference, andcontrols the driving section to bring the touch probe into contact withthe inclined surface of the workpiece with the specified fourth contacttarget position for measurement as a reference; and a measuring sectionwhich measures three-dimensional coordinates of a contact point at whichthe touch probe comes into contact with the workpiece based on thecontact signal output when the touch probe comes into contact with theworkpiece by an operation of the driving section controlled by thecontrol section.